Logistic distribution

Percentage Accurate: 99.5% → 99.5%

Time: 8.1s

Alternatives: 14

Speedup: 1.1×

Specification

\[0 \leq s \land s \leq 1.0651631\]

Math

\[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\right|}{s}}\\ t_1 := 1 + t\_0\\ \frac{t\_0}{\left(s \cdot t\_1\right) \cdot t\_1} \end{array} \end{array} \]

FPCore

(FPCore (x s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x)) s))) (t_1 (+ 1.0 t_0)))
   (/ t_0 (* (* s t_1) t_1))))

C

float code(float x, float s) {
	float t_0 = expf((-fabsf(x) / s));
	float t_1 = 1.0f + t_0;
	return t_0 / ((s * t_1) * t_1);
}

Fortran

real(4) function code(x, s)
    real(4), intent (in) :: x
    real(4), intent (in) :: s
    real(4) :: t_0
    real(4) :: t_1
    t_0 = exp((-abs(x) / s))
    t_1 = 1.0e0 + t_0
    code = t_0 / ((s * t_1) * t_1)
end function

Julia

function code(x, s)
	t_0 = exp(Float32(Float32(-abs(x)) / s))
	t_1 = Float32(Float32(1.0) + t_0)
	return Float32(t_0 / Float32(Float32(s * t_1) * t_1))
end

MATLAB

function tmp = code(x, s)
	t_0 = exp((-abs(x) / s));
	t_1 = single(1.0) + t_0;
	tmp = t_0 / ((s * t_1) * t_1);
end

Initial Program: 99.5% accurate, 1.0× speedup

Math

\[\begin{array}{l} \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\right|}{s}}\\ t_1 := 1 + t\_0\\ \frac{t\_0}{\left(s \cdot t\_1\right) \cdot t\_1} \end{array} \end{array} \]

FPCore

(FPCore (x s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x)) s))) (t_1 (+ 1.0 t_0)))
   (/ t_0 (* (* s t_1) t_1))))

C

float code(float x, float s) {
	float t_0 = expf((-fabsf(x) / s));
	float t_1 = 1.0f + t_0;
	return t_0 / ((s * t_1) * t_1);
}

Fortran

real(4) function code(x, s)
    real(4), intent (in) :: x
    real(4), intent (in) :: s
    real(4) :: t_0
    real(4) :: t_1
    t_0 = exp((-abs(x) / s))
    t_1 = 1.0e0 + t_0
    code = t_0 / ((s * t_1) * t_1)
end function

Julia

function code(x, s)
	t_0 = exp(Float32(Float32(-abs(x)) / s))
	t_1 = Float32(Float32(1.0) + t_0)
	return Float32(t_0 / Float32(Float32(s * t_1) * t_1))
end

MATLAB

function tmp = code(x, s)
	t_0 = exp((-abs(x) / s));
	t_1 = single(1.0) + t_0;
	tmp = t_0 / ((s * t_1) * t_1);
end

Alternative 1: 99.5% accurate, 1.0× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-x\_m}{s}}\\ \frac{t\_0}{\left(1 + t\_0\right) \cdot \left(\frac{s}{e^{\frac{x\_m}{s}}} + s\right)} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- x_m) s))))
   (/ t_0 (* (+ 1.0 t_0) (+ (/ s (exp (/ x_m s))) s)))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-x_m / s));
	return t_0 / ((1.0f + t_0) * ((s / expf((x_m / s))) + s));
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-x_m / s))
    code = t_0 / ((1.0e0 + t_0) * ((s / exp((x_m / s))) + s))
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-x_m) / s))
	return Float32(t_0 / Float32(Float32(Float32(1.0) + t_0) * Float32(Float32(s / exp(Float32(x_m / s))) + s)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-x_m / s));
	tmp = t_0 / ((single(1.0) + t_0) * ((s / exp((x_m / s))) + s));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. lift-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(e^{\frac{-\left|x\right|}{s}} + 1\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. distribute-lft-in N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s \cdot 1\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. *-rgt-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + \color{blue}{s}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

4. Applied rewrites 97.0%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
5. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{-\left|x\right|}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. frac-2neg N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(\left(-\left|x\right|\right)\right)}{\mathsf{neg}\left(s\right)}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. lift-neg.f32 N/A

      \[\leadsto \frac{e^{\frac{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\left|x\right|\right)\right)}\right)}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. remove-double-neg N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. lift-fabs.f32 N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. rem-sqrt-square-rev N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x \cdot x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   7. sqrt-prod N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x} \cdot \sqrt{x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   8. rem-square-sqrt N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{x}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   9. distribute-neg-frac2 N/A

      \[\leadsto \frac{e^{\color{blue}{\mathsf{neg}\left(\frac{x}{s}\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   10. distribute-frac-neg N/A

       \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(x\right)}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   11. lift-neg.f32 N/A

       \[\leadsto \frac{e^{\frac{\color{blue}{-x}}{s}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   12. lift-/.f32 59.5

       \[\leadsto \frac{e^{\color{blue}{\frac{-x}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   13. lift-*.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   14. *-commutative N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

   15. lower-*.f32 59.5

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

6. Applied rewrites 62.3%

   \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]
7. Add Preprocessing

Alternative 2: 29.5% accurate, 0.9× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ t_1 := 1 + t\_0\\ \mathbf{if}\;\frac{t\_0}{\left(s \cdot t\_1\right) \cdot t\_1} \leq 0:\\ \;\;\;\;\frac{\frac{-0.0625}{s} \cdot \frac{x\_m \cdot x\_m}{s}}{s}\\ \mathbf{else}:\\ \;\;\;\;\frac{0.25 + \frac{-0.25}{s} \cdot \left(\left(\frac{x\_m}{s} \cdot x\_m\right) \cdot 0.25\right)}{s}\\ \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))) (t_1 (+ 1.0 t_0)))
   (if (<= (/ t_0 (* (* s t_1) t_1)) 0.0)
     (/ (* (/ -0.0625 s) (/ (* x_m x_m) s)) s)
     (/ (+ 0.25 (* (/ -0.25 s) (* (* (/ x_m s) x_m) 0.25))) s))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	float t_1 = 1.0f + t_0;
	float tmp;
	if ((t_0 / ((s * t_1) * t_1)) <= 0.0f) {
		tmp = ((-0.0625f / s) * ((x_m * x_m) / s)) / s;
	} else {
		tmp = (0.25f + ((-0.25f / s) * (((x_m / s) * x_m) * 0.25f))) / s;
	}
	return tmp;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    real(4) :: t_1
    real(4) :: tmp
    t_0 = exp((-abs(x_m) / s))
    t_1 = 1.0e0 + t_0
    if ((t_0 / ((s * t_1) * t_1)) <= 0.0e0) then
        tmp = (((-0.0625e0) / s) * ((x_m * x_m) / s)) / s
    else
        tmp = (0.25e0 + (((-0.25e0) / s) * (((x_m / s) * x_m) * 0.25e0))) / s
    end if
    code = tmp
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	t_1 = Float32(Float32(1.0) + t_0)
	tmp = Float32(0.0)
	if (Float32(t_0 / Float32(Float32(s * t_1) * t_1)) <= Float32(0.0))
		tmp = Float32(Float32(Float32(Float32(-0.0625) / s) * Float32(Float32(x_m * x_m) / s)) / s);
	else
		tmp = Float32(Float32(Float32(0.25) + Float32(Float32(Float32(-0.25) / s) * Float32(Float32(Float32(x_m / s) * x_m) * Float32(0.25)))) / s);
	end
	return tmp
end

MATLAB

x_m = abs(x);
function tmp_2 = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	t_1 = single(1.0) + t_0;
	tmp = single(0.0);
	if ((t_0 / ((s * t_1) * t_1)) <= single(0.0))
		tmp = ((single(-0.0625) / s) * ((x_m * x_m) / s)) / s;
	else
		tmp = (single(0.25) + ((single(-0.25) / s) * (((x_m / s) * x_m) * single(0.25)))) / s;
	end
	tmp_2 = tmp;
end

Derivation

1. Split input into 2 regimes

2. if (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s))))) < 0.0

   1. Initial program 100.0%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift-/.f32 N/A

         \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      2. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      3. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

      4. associate-*l* N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

      5. *-commutative N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

      6. associate-/r* N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

      7. lower-/.f32 N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   4. Applied rewrites 76.5%

      \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \frac{\color{blue}{e^{\mathsf{neg}\left(2 \cdot \log 2\right)} + \frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}}}}{s} \]
   6. Step-by-step derivation

      1. +-commutative N/A

         \[\leadsto \frac{\color{blue}{\frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}} + e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}}{s} \]

   7. Applied rewrites 4.5%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(\frac{-0.25}{s}, \frac{\left(x \cdot x\right) \cdot 0.25}{s}, 0.25\right)}}{s} \]

   8. Taylor expanded in x around inf

      \[\leadsto \frac{\frac{-1}{16} \cdot \color{blue}{\frac{{x}^{2}}{{s}^{2}}}}{s} \]
   9. Step-by-step derivation

   10. Applied rewrites 10.0%

       \[\leadsto \frac{\frac{-0.0625}{s} \cdot \color{blue}{\frac{x \cdot x}{s}}}{s} \]

   if 0.0 < (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))))

   1. Initial program 99.1%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift-/.f32 N/A

         \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      2. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      3. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

      4. associate-*l* N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

      5. *-commutative N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

      6. associate-/r* N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

      7. lower-/.f32 N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   4. Applied rewrites 24.8%

      \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \frac{\color{blue}{e^{\mathsf{neg}\left(2 \cdot \log 2\right)} + \frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}}}}{s} \]
   6. Step-by-step derivation

      1. +-commutative N/A

         \[\leadsto \frac{\color{blue}{\frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}} + e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}}{s} \]

   7. Applied rewrites 87.1%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(\frac{-0.25}{s}, \frac{\left(x \cdot x\right) \cdot 0.25}{s}, 0.25\right)}}{s} \]
   8. Step-by-step derivation

   9. Applied rewrites 87.1%

      \[\leadsto \frac{\mathsf{fma}\left(\frac{-0.25}{s}, \color{blue}{\frac{0.25 \cdot \left(x \cdot x\right)}{s}}, 0.25\right)}{s} \]
   10. Step-by-step derivation

   11. Applied rewrites 90.9%

       \[\leadsto \frac{0.25 - \color{blue}{\left(-\frac{-0.25}{s}\right) \cdot \left(\left(\frac{x}{s} \cdot x\right) \cdot 0.25\right)}}{s} \]
3. Recombined 2 regimes into one program.

4. Final simplification 31.8%

   \[\leadsto \begin{array}{l} \mathbf{if}\;\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \leq 0:\\ \;\;\;\;\frac{\frac{-0.0625}{s} \cdot \frac{x \cdot x}{s}}{s}\\ \mathbf{else}:\\ \;\;\;\;\frac{0.25 + \frac{-0.25}{s} \cdot \left(\left(\frac{x}{s} \cdot x\right) \cdot 0.25\right)}{s}\\ \end{array} \]
5. Add Preprocessing

Alternative 3: 29.3% accurate, 0.9× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ t_1 := 1 + t\_0\\ \mathbf{if}\;\frac{t\_0}{\left(s \cdot t\_1\right) \cdot t\_1} \leq 0:\\ \;\;\;\;\frac{\frac{-0.0625}{s} \cdot \frac{x\_m \cdot x\_m}{s}}{s}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{\frac{-0.0625 \cdot \left(x\_m \cdot x\_m\right)}{s}}{s} + 0.25}{s}\\ \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))) (t_1 (+ 1.0 t_0)))
   (if (<= (/ t_0 (* (* s t_1) t_1)) 0.0)
     (/ (* (/ -0.0625 s) (/ (* x_m x_m) s)) s)
     (/ (+ (/ (/ (* -0.0625 (* x_m x_m)) s) s) 0.25) s))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	float t_1 = 1.0f + t_0;
	float tmp;
	if ((t_0 / ((s * t_1) * t_1)) <= 0.0f) {
		tmp = ((-0.0625f / s) * ((x_m * x_m) / s)) / s;
	} else {
		tmp = ((((-0.0625f * (x_m * x_m)) / s) / s) + 0.25f) / s;
	}
	return tmp;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    real(4) :: t_1
    real(4) :: tmp
    t_0 = exp((-abs(x_m) / s))
    t_1 = 1.0e0 + t_0
    if ((t_0 / ((s * t_1) * t_1)) <= 0.0e0) then
        tmp = (((-0.0625e0) / s) * ((x_m * x_m) / s)) / s
    else
        tmp = (((((-0.0625e0) * (x_m * x_m)) / s) / s) + 0.25e0) / s
    end if
    code = tmp
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	t_1 = Float32(Float32(1.0) + t_0)
	tmp = Float32(0.0)
	if (Float32(t_0 / Float32(Float32(s * t_1) * t_1)) <= Float32(0.0))
		tmp = Float32(Float32(Float32(Float32(-0.0625) / s) * Float32(Float32(x_m * x_m) / s)) / s);
	else
		tmp = Float32(Float32(Float32(Float32(Float32(Float32(-0.0625) * Float32(x_m * x_m)) / s) / s) + Float32(0.25)) / s);
	end
	return tmp
end

MATLAB

x_m = abs(x);
function tmp_2 = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	t_1 = single(1.0) + t_0;
	tmp = single(0.0);
	if ((t_0 / ((s * t_1) * t_1)) <= single(0.0))
		tmp = ((single(-0.0625) / s) * ((x_m * x_m) / s)) / s;
	else
		tmp = ((((single(-0.0625) * (x_m * x_m)) / s) / s) + single(0.25)) / s;
	end
	tmp_2 = tmp;
end

Derivation

1. Split input into 2 regimes

2. if (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s))))) < 0.0

   1. Initial program 100.0%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift-/.f32 N/A

         \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      2. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      3. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

      4. associate-*l* N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

      5. *-commutative N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

      6. associate-/r* N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

      7. lower-/.f32 N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   4. Applied rewrites 76.5%

      \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \frac{\color{blue}{e^{\mathsf{neg}\left(2 \cdot \log 2\right)} + \frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}}}}{s} \]
   6. Step-by-step derivation

      1. +-commutative N/A

         \[\leadsto \frac{\color{blue}{\frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}} + e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}}{s} \]

   7. Applied rewrites 4.5%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(\frac{-0.25}{s}, \frac{\left(x \cdot x\right) \cdot 0.25}{s}, 0.25\right)}}{s} \]

   8. Taylor expanded in x around inf

      \[\leadsto \frac{\frac{-1}{16} \cdot \color{blue}{\frac{{x}^{2}}{{s}^{2}}}}{s} \]
   9. Step-by-step derivation

   10. Applied rewrites 10.0%

       \[\leadsto \frac{\frac{-0.0625}{s} \cdot \color{blue}{\frac{x \cdot x}{s}}}{s} \]

   if 0.0 < (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))))

   1. Initial program 99.1%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift-/.f32 N/A

         \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      2. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      3. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

      4. associate-*l* N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

      5. *-commutative N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

      6. associate-/r* N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

      7. lower-/.f32 N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   4. Applied rewrites 24.8%

      \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \frac{\color{blue}{e^{\mathsf{neg}\left(2 \cdot \log 2\right)} + \frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}}}}{s} \]
   6. Step-by-step derivation

      1. +-commutative N/A

         \[\leadsto \frac{\color{blue}{\frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}} + e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}}{s} \]

   7. Applied rewrites 88.6%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(\frac{-0.25}{s}, \frac{\left(x \cdot x\right) \cdot 0.25}{s}, 0.25\right)}}{s} \]
   8. Step-by-step derivation

   9. Applied rewrites 90.1%

      \[\leadsto \frac{\frac{\frac{-0.0625 \cdot \left(x \cdot x\right)}{s}}{s} + \color{blue}{0.25}}{s} \]
3. Recombined 2 regimes into one program.
4. Add Preprocessing

Alternative 4: 29.0% accurate, 0.9× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ t_1 := 1 + t\_0\\ \mathbf{if}\;\frac{t\_0}{\left(s \cdot t\_1\right) \cdot t\_1} \leq 0:\\ \;\;\;\;\frac{\frac{-0.0625}{s} \cdot \frac{x\_m \cdot x\_m}{s}}{s}\\ \mathbf{else}:\\ \;\;\;\;\frac{0.25}{s}\\ \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))) (t_1 (+ 1.0 t_0)))
   (if (<= (/ t_0 (* (* s t_1) t_1)) 0.0)
     (/ (* (/ -0.0625 s) (/ (* x_m x_m) s)) s)
     (/ 0.25 s))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	float t_1 = 1.0f + t_0;
	float tmp;
	if ((t_0 / ((s * t_1) * t_1)) <= 0.0f) {
		tmp = ((-0.0625f / s) * ((x_m * x_m) / s)) / s;
	} else {
		tmp = 0.25f / s;
	}
	return tmp;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    real(4) :: t_1
    real(4) :: tmp
    t_0 = exp((-abs(x_m) / s))
    t_1 = 1.0e0 + t_0
    if ((t_0 / ((s * t_1) * t_1)) <= 0.0e0) then
        tmp = (((-0.0625e0) / s) * ((x_m * x_m) / s)) / s
    else
        tmp = 0.25e0 / s
    end if
    code = tmp
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	t_1 = Float32(Float32(1.0) + t_0)
	tmp = Float32(0.0)
	if (Float32(t_0 / Float32(Float32(s * t_1) * t_1)) <= Float32(0.0))
		tmp = Float32(Float32(Float32(Float32(-0.0625) / s) * Float32(Float32(x_m * x_m) / s)) / s);
	else
		tmp = Float32(Float32(0.25) / s);
	end
	return tmp
end

MATLAB

x_m = abs(x);
function tmp_2 = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	t_1 = single(1.0) + t_0;
	tmp = single(0.0);
	if ((t_0 / ((s * t_1) * t_1)) <= single(0.0))
		tmp = ((single(-0.0625) / s) * ((x_m * x_m) / s)) / s;
	else
		tmp = single(0.25) / s;
	end
	tmp_2 = tmp;
end

Derivation

1. Split input into 2 regimes

2. if (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s))))) < 0.0

   1. Initial program 100.0%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift-/.f32 N/A

         \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      2. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

      3. lift-*.f32 N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

      4. associate-*l* N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

      5. *-commutative N/A

         \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

      6. associate-/r* N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

      7. lower-/.f32 N/A

         \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   4. Applied rewrites 76.5%

      \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \frac{\color{blue}{e^{\mathsf{neg}\left(2 \cdot \log 2\right)} + \frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}}}}{s} \]
   6. Step-by-step derivation

      1. +-commutative N/A

         \[\leadsto \frac{\color{blue}{\frac{-1}{4} \cdot \frac{{x}^{2} \cdot e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}{{s}^{2}} + e^{\mathsf{neg}\left(2 \cdot \log 2\right)}}}{s} \]

   7. Applied rewrites 4.5%

      \[\leadsto \frac{\color{blue}{\mathsf{fma}\left(\frac{-0.25}{s}, \frac{\left(x \cdot x\right) \cdot 0.25}{s}, 0.25\right)}}{s} \]

   8. Taylor expanded in x around inf

      \[\leadsto \frac{\frac{-1}{16} \cdot \color{blue}{\frac{{x}^{2}}{{s}^{2}}}}{s} \]
   9. Step-by-step derivation

   10. Applied rewrites 10.0%

       \[\leadsto \frac{\frac{-0.0625}{s} \cdot \color{blue}{\frac{x \cdot x}{s}}}{s} \]

   if 0.0 < (/.f32 (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)) (*.f32 (*.f32 s (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (fabs.f32 x)) s)))))

   1. Initial program 99.1%

      \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
   2. Add Preprocessing

   3. Taylor expanded in s around inf

      \[\leadsto \color{blue}{\frac{\frac{1}{4}}{s}} \]
   4. Step-by-step derivation

      1. lower-/.f32 88.6

         \[\leadsto \color{blue}{\frac{0.25}{s}} \]

   5. Applied rewrites 88.6%

      \[\leadsto \color{blue}{\frac{0.25}{s}} \]
3. Recombined 2 regimes into one program.
4. Add Preprocessing

Alternative 5: 99.5% accurate, 1.1× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \frac{\frac{e^{\frac{-x\_m}{s}}}{s}}{{\left(1 + e^{\frac{-\left|x\_m\right|}{s}}\right)}^{2}} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (/ (/ (exp (/ (- x_m) s)) s) (pow (+ 1.0 (exp (/ (- (fabs x_m)) s))) 2.0)))

C

x_m = fabs(x);
float code(float x_m, float s) {
	return (expf((-x_m / s)) / s) / powf((1.0f + expf((-fabsf(x_m) / s))), 2.0f);
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    code = (exp((-x_m / s)) / s) / ((1.0e0 + exp((-abs(x_m) / s))) ** 2.0e0)
end function

Julia

x_m = abs(x)
function code(x_m, s)
	return Float32(Float32(exp(Float32(Float32(-x_m) / s)) / s) / (Float32(Float32(1.0) + exp(Float32(Float32(-abs(x_m)) / s))) ^ Float32(2.0)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	tmp = (exp((-x_m / s)) / s) / ((single(1.0) + exp((-abs(x_m) / s))) ^ single(2.0));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing

3. Taylor expanded in x around 0

   \[\leadsto \color{blue}{\frac{e^{-1 \cdot \frac{\left|x\right|}{s}}}{s \cdot {\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}}} \]
4. Step-by-step derivation

   1. associate-/r* N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{-1 \cdot \frac{\left|x\right|}{s}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}}} \]

   2. lower-/.f32 N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{-1 \cdot \frac{\left|x\right|}{s}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}}} \]

   3. lower-/.f32 N/A

      \[\leadsto \frac{\color{blue}{\frac{e^{-1 \cdot \frac{\left|x\right|}{s}}}{s}}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   4. lower-exp.f32 N/A

      \[\leadsto \frac{\frac{\color{blue}{e^{-1 \cdot \frac{\left|x\right|}{s}}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   5. mul-1-neg N/A

      \[\leadsto \frac{\frac{e^{\color{blue}{\mathsf{neg}\left(\frac{\left|x\right|}{s}\right)}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   6. distribute-neg-frac2 N/A

      \[\leadsto \frac{\frac{e^{\color{blue}{\frac{\left|x\right|}{\mathsf{neg}\left(s\right)}}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   7. lower-/.f32 N/A

      \[\leadsto \frac{\frac{e^{\color{blue}{\frac{\left|x\right|}{\mathsf{neg}\left(s\right)}}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   8. lower-fabs.f32 N/A

      \[\leadsto \frac{\frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   9. lower-neg.f32 N/A

      \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{\color{blue}{-s}}}}{s}}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}} \]

   10. lower-pow.f32 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{\color{blue}{{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}^{2}}} \]

   11. lower-+.f32 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\color{blue}{\left(1 + e^{-1 \cdot \frac{\left|x\right|}{s}}\right)}}^{2}} \]

   12. lower-exp.f32 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + \color{blue}{e^{-1 \cdot \frac{\left|x\right|}{s}}}\right)}^{2}} \]

   13. mul-1-neg N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\color{blue}{\mathsf{neg}\left(\frac{\left|x\right|}{s}\right)}}\right)}^{2}} \]

   14. distribute-neg-frac2 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\color{blue}{\frac{\left|x\right|}{\mathsf{neg}\left(s\right)}}}\right)}^{2}} \]

   15. lower-/.f32 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\color{blue}{\frac{\left|x\right|}{\mathsf{neg}\left(s\right)}}}\right)}^{2}} \]

   16. lower-fabs.f32 N/A

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}\right)}^{2}} \]

   17. lower-neg.f32 99.8

       \[\leadsto \frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\frac{\left|x\right|}{\color{blue}{-s}}}\right)}^{2}} \]

5. Applied rewrites 99.8%

   \[\leadsto \color{blue}{\frac{\frac{e^{\frac{\left|x\right|}{-s}}}{s}}{{\left(1 + e^{\frac{\left|x\right|}{-s}}\right)}^{2}}} \]
6. Step-by-step derivation

7. Applied rewrites 60.4%

   \[\leadsto \frac{\frac{e^{\frac{-x}{s}}}{s}}{{\color{blue}{\left(1 + e^{\frac{\left|x\right|}{-s}}\right)}}^{2}} \]

8. Final simplification 60.4%

   \[\leadsto \frac{\frac{e^{\frac{-x}{s}}}{s}}{{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}^{2}} \]
9. Add Preprocessing

Alternative 6: 99.5% accurate, 1.1× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := \frac{-x\_m}{s}\\ \frac{e^{t\_0 - \log \left(1 + e^{t\_0}\right) \cdot 2}}{s} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (/ (- x_m) s)))
   (/ (exp (- t_0 (* (log (+ 1.0 (exp t_0))) 2.0))) s)))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = -x_m / s;
	return expf((t_0 - (logf((1.0f + expf(t_0))) * 2.0f))) / s;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = -x_m / s
    code = exp((t_0 - (log((1.0e0 + exp(t_0))) * 2.0e0))) / s
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = Float32(Float32(-x_m) / s)
	return Float32(exp(Float32(t_0 - Float32(log(Float32(Float32(1.0) + exp(t_0))) * Float32(2.0)))) / s)
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = -x_m / s;
	tmp = exp((t_0 - (log((single(1.0) + exp(t_0))) * single(2.0)))) / s;
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   2. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   3. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. associate-*l* N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

   5. *-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

   6. associate-/r* N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   7. lower-/.f32 N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

4. Applied rewrites 62.8%

   \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]
5. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\color{blue}{\frac{-x}{s}}}\right) \cdot 2}}{s} \]

   2. frac-2neg N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\color{blue}{\frac{\mathsf{neg}\left(\left(-x\right)\right)}{\mathsf{neg}\left(s\right)}}}\right) \cdot 2}}{s} \]

   3. lift-neg.f32 N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right)}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   4. remove-double-neg N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{x}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   5. rem-square-sqrt N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{\sqrt{x} \cdot \sqrt{x}}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   6. sqrt-prod N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{\sqrt{x \cdot x}}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   7. rem-sqrt-square-rev N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   8. lift-fabs.f32 N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   9. distribute-frac-neg2 N/A

      \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\color{blue}{\mathsf{neg}\left(\frac{\left|x\right|}{s}\right)}}\right) \cdot 2}}{s} \]

   10. distribute-frac-neg N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\color{blue}{\frac{\mathsf{neg}\left(\left|x\right|\right)}{s}}}\right) \cdot 2}}{s} \]

   11. lift-neg.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{\color{blue}{-\left|x\right|}}{s}}\right) \cdot 2}}{s} \]

   12. lift-/.f32 43.4

       \[\leadsto \frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\color{blue}{\frac{-\left|x\right|}{s}}}\right) \cdot 2}}{s} \]

   13. lower-log1p.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \cdot 2}}{s} \]

   14. lift-+.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \cdot 2}}{s} \]

   15. lower-log.f32 60.5

       \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \cdot 2}}{s} \]

   16. lift-/.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\color{blue}{\frac{-\left|x\right|}{s}}}\right) \cdot 2}}{s} \]

   17. frac-2neg N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\color{blue}{\frac{\mathsf{neg}\left(\left(-\left|x\right|\right)\right)}{\mathsf{neg}\left(s\right)}}}\right) \cdot 2}}{s} \]

   18. lift-neg.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\left|x\right|\right)\right)}\right)}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   19. remove-double-neg N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   20. lift-fabs.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   21. rem-sqrt-square-rev N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\color{blue}{\sqrt{x \cdot x}}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   22. sqrt-prod N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\color{blue}{\sqrt{x} \cdot \sqrt{x}}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

   23. rem-square-sqrt N/A

       \[\leadsto \frac{e^{\frac{-x}{s} - \log \left(1 + e^{\frac{\color{blue}{x}}{\mathsf{neg}\left(s\right)}}\right) \cdot 2}}{s} \]

6. Applied rewrites 82.5%

   \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log \left(1 + e^{\frac{-x}{s}}\right)} \cdot 2}}{s} \]
7. Add Preprocessing

Alternative 7: 97.1% accurate, 1.3× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ \frac{t\_0}{\left(\left(\frac{\left(\frac{x\_m}{s} \cdot x\_m\right) \cdot 0.5 - x\_m}{s} - -1\right) \cdot s + s\right) \cdot \left(1 + t\_0\right)} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))))
   (/
    t_0
    (*
     (+ (* (- (/ (- (* (* (/ x_m s) x_m) 0.5) x_m) s) -1.0) s) s)
     (+ 1.0 t_0)))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	return t_0 / (((((((((x_m / s) * x_m) * 0.5f) - x_m) / s) - -1.0f) * s) + s) * (1.0f + t_0));
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-abs(x_m) / s))
    code = t_0 / (((((((((x_m / s) * x_m) * 0.5e0) - x_m) / s) - (-1.0e0)) * s) + s) * (1.0e0 + t_0))
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	return Float32(t_0 / Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(x_m / s) * x_m) * Float32(0.5)) - x_m) / s) - Float32(-1.0)) * s) + s) * Float32(Float32(1.0) + t_0)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	tmp = t_0 / (((((((((x_m / s) * x_m) * single(0.5)) - x_m) / s) - single(-1.0)) * s) + s) * (single(1.0) + t_0));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. lift-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(e^{\frac{-\left|x\right|}{s}} + 1\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. distribute-lft-in N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s \cdot 1\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. *-rgt-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + \color{blue}{s}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

4. Applied rewrites 97.0%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

5. Taylor expanded in s around -inf

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{-1 \cdot \left(s \cdot \left(-1 \cdot \frac{\left(\frac{-1}{2} \cdot \frac{{x}^{2}}{s} + \frac{{x}^{2}}{s}\right) - x}{s} - 1\right)\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

7. Applied rewrites 96.1%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{\left(\frac{\frac{x \cdot x}{s} \cdot 0.5 - x}{-s} - 1\right) \cdot \left(-s\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
8. Step-by-step derivation

9. Applied rewrites 96.1%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\left(\frac{\left(\frac{x}{s} \cdot x\right) \cdot 0.5 - x}{-s} - 1\right) \cdot \left(-s\right) + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

10. Final simplification 96.1%

    \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\left(\frac{\left(\frac{x}{s} \cdot x\right) \cdot 0.5 - x}{s} - -1\right) \cdot s + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
11. Add Preprocessing

Alternative 8: 97.0% accurate, 1.4× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-x\_m}{s}}\\ \frac{t\_0}{\left(1 + t\_0\right) \cdot \left(\frac{s}{\frac{x\_m}{s} + 1} + s\right)} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- x_m) s))))
   (/ t_0 (* (+ 1.0 t_0) (+ (/ s (+ (/ x_m s) 1.0)) s)))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-x_m / s));
	return t_0 / ((1.0f + t_0) * ((s / ((x_m / s) + 1.0f)) + s));
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-x_m / s))
    code = t_0 / ((1.0e0 + t_0) * ((s / ((x_m / s) + 1.0e0)) + s))
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-x_m) / s))
	return Float32(t_0 / Float32(Float32(Float32(1.0) + t_0) * Float32(Float32(s / Float32(Float32(x_m / s) + Float32(1.0))) + s)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-x_m / s));
	tmp = t_0 / ((single(1.0) + t_0) * ((s / ((x_m / s) + single(1.0))) + s));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. lift-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(e^{\frac{-\left|x\right|}{s}} + 1\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. distribute-lft-in N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s \cdot 1\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. *-rgt-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + \color{blue}{s}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

4. Applied rewrites 97.0%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
5. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{-\left|x\right|}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. frac-2neg N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(\left(-\left|x\right|\right)\right)}{\mathsf{neg}\left(s\right)}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. lift-neg.f32 N/A

      \[\leadsto \frac{e^{\frac{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\left|x\right|\right)\right)}\right)}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. remove-double-neg N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. lift-fabs.f32 N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. rem-sqrt-square-rev N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x \cdot x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   7. sqrt-prod N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x} \cdot \sqrt{x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   8. rem-square-sqrt N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{x}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   9. distribute-neg-frac2 N/A

      \[\leadsto \frac{e^{\color{blue}{\mathsf{neg}\left(\frac{x}{s}\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   10. distribute-frac-neg N/A

       \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(x\right)}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   11. lift-neg.f32 N/A

       \[\leadsto \frac{e^{\frac{\color{blue}{-x}}{s}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   12. lift-/.f32 59.5

       \[\leadsto \frac{e^{\color{blue}{\frac{-x}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   13. lift-*.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   14. *-commutative N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

   15. lower-*.f32 59.5

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

6. Applied rewrites 62.3%

   \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

7. Taylor expanded in x around 0

   \[\leadsto \frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{\color{blue}{1 + \frac{x}{s}}} + s\right)} \]
8. Step-by-step derivation

   1. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{\color{blue}{\frac{x}{s} + 1}} + s\right)} \]

   2. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{\color{blue}{\frac{x}{s} + 1}} + s\right)} \]

   3. lower-/.f32 59.4

      \[\leadsto \frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{\color{blue}{\frac{x}{s}} + 1} + s\right)} \]

9. Applied rewrites 59.4%

   \[\leadsto \frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{\color{blue}{\frac{x}{s} + 1}} + s\right)} \]
10. Add Preprocessing

Alternative 9: 96.2% accurate, 1.4× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ \frac{t\_0}{\left(s \cdot \left(1 + t\_0\right)\right) \cdot \left(2 - \frac{\left|x\_m\right|}{s}\right)} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))))
   (/ t_0 (* (* s (+ 1.0 t_0)) (- 2.0 (/ (fabs x_m) s))))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	return t_0 / ((s * (1.0f + t_0)) * (2.0f - (fabsf(x_m) / s)));
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-abs(x_m) / s))
    code = t_0 / ((s * (1.0e0 + t_0)) * (2.0e0 - (abs(x_m) / s)))
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	return Float32(t_0 / Float32(Float32(s * Float32(Float32(1.0) + t_0)) * Float32(Float32(2.0) - Float32(abs(x_m) / s))))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	tmp = t_0 / ((s * (single(1.0) + t_0)) * (single(2.0) - (abs(x_m) / s)));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing

3. Taylor expanded in s around inf

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{\left(2 + -1 \cdot \frac{\left|x\right|}{s}\right)}} \]
4. Step-by-step derivation

   1. fp-cancel-sign-sub-inv N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{\left(2 - \left(\mathsf{neg}\left(-1\right)\right) \cdot \frac{\left|x\right|}{s}\right)}} \]

   2. metadata-eval N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(2 - \color{blue}{1} \cdot \frac{\left|x\right|}{s}\right)} \]

   3. *-lft-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(2 - \color{blue}{\frac{\left|x\right|}{s}}\right)} \]

   4. lower--.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{\left(2 - \frac{\left|x\right|}{s}\right)}} \]

   5. lower-/.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(2 - \color{blue}{\frac{\left|x\right|}{s}}\right)} \]

   6. lower-fabs.f32 96.6

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(2 - \frac{\color{blue}{\left|x\right|}}{s}\right)} \]

5. Applied rewrites 96.6%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{\left(2 - \frac{\left|x\right|}{s}\right)}} \]
6. Add Preprocessing

Alternative 10: 96.2% accurate, 1.5× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ \frac{t\_0}{\left(\left(s - x\_m\right) + s\right) \cdot \left(1 + t\_0\right)} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s))))
   (/ t_0 (* (+ (- s x_m) s) (+ 1.0 t_0)))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	return t_0 / (((s - x_m) + s) * (1.0f + t_0));
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-abs(x_m) / s))
    code = t_0 / (((s - x_m) + s) * (1.0e0 + t_0))
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	return Float32(t_0 / Float32(Float32(Float32(s - x_m) + s) * Float32(Float32(1.0) + t_0)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	tmp = t_0 / (((s - x_m) + s) * (single(1.0) + t_0));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. lift-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(e^{\frac{-\left|x\right|}{s}} + 1\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. distribute-lft-in N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s \cdot 1\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. *-rgt-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + \color{blue}{s}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

4. Applied rewrites 97.0%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

5. Taylor expanded in x around 0

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{\left(s + -1 \cdot x\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
6. Step-by-step derivation

   1. mul-1-neg N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\left(s + \color{blue}{\left(\mathsf{neg}\left(x\right)\right)}\right) + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{\left(\left(\mathsf{neg}\left(x\right)\right) + s\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. mul-1-neg N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\left(\color{blue}{-1 \cdot x} + s\right) + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. lower-fma.f32 75.6

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{\mathsf{fma}\left(-1, x, s\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

7. Applied rewrites 75.9%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(\color{blue}{\mathsf{fma}\left(-1, x, s\right)} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
8. Step-by-step derivation

9. Applied rewrites 95.8%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(s - x\right) + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
10. Add Preprocessing

Alternative 11: 95.3% accurate, 1.5× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \begin{array}{l} t_0 := e^{\frac{-\left|x\_m\right|}{s}}\\ \frac{t\_0}{\left(s \cdot \left(1 + t\_0\right)\right) \cdot 2} \end{array} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (let* ((t_0 (exp (/ (- (fabs x_m)) s)))) (/ t_0 (* (* s (+ 1.0 t_0)) 2.0))))

C

x_m = fabs(x);
float code(float x_m, float s) {
	float t_0 = expf((-fabsf(x_m) / s));
	return t_0 / ((s * (1.0f + t_0)) * 2.0f);
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    real(4) :: t_0
    t_0 = exp((-abs(x_m) / s))
    code = t_0 / ((s * (1.0e0 + t_0)) * 2.0e0)
end function

Julia

x_m = abs(x)
function code(x_m, s)
	t_0 = exp(Float32(Float32(-abs(x_m)) / s))
	return Float32(t_0 / Float32(Float32(s * Float32(Float32(1.0) + t_0)) * Float32(2.0)))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	t_0 = exp((-abs(x_m) / s));
	tmp = t_0 / ((s * (single(1.0) + t_0)) * single(2.0));
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing

3. Taylor expanded in s around inf

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{2}} \]
4. Step-by-step derivation

5. Applied rewrites 95.4%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \color{blue}{2}} \]
6. Add Preprocessing

Alternative 12: 95.0% accurate, 1.6× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \frac{e^{\frac{-x\_m}{s} - \log 2 \cdot 2}}{s} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s)
 :precision binary32
 (/ (exp (- (/ (- x_m) s) (* (log 2.0) 2.0))) s))

C

x_m = fabs(x);
float code(float x_m, float s) {
	return expf(((-x_m / s) - (logf(2.0f) * 2.0f))) / s;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    code = exp(((-x_m / s) - (log(2.0e0) * 2.0e0))) / s
end function

Julia

x_m = abs(x)
function code(x_m, s)
	return Float32(exp(Float32(Float32(Float32(-x_m) / s) - Float32(log(Float32(2.0)) * Float32(2.0)))) / s)
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	tmp = exp(((-x_m / s) - (log(single(2.0)) * single(2.0)))) / s;
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \color{blue}{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   2. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   3. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. associate-*l* N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{s \cdot \left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)}} \]

   5. *-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot s}} \]

   6. associate-/r* N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

   7. lower-/.f32 N/A

      \[\leadsto \color{blue}{\frac{\frac{e^{\frac{-\left|x\right|}{s}}}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}}{s}} \]

4. Applied rewrites 62.8%

   \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s} - \mathsf{log1p}\left(e^{\frac{-x}{s}}\right) \cdot 2}}{s}} \]

5. Taylor expanded in x around 0

   \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log 2} \cdot 2}}{s} \]
6. Step-by-step derivation

   1. lower-log.f32 58.7

      \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log 2} \cdot 2}}{s} \]

7. Applied rewrites 58.7%

   \[\leadsto \frac{e^{\frac{-x}{s} - \color{blue}{\log 2} \cdot 2}}{s} \]
8. Add Preprocessing

Alternative 13: 95.0% accurate, 2.9× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \frac{e^{\frac{-x\_m}{s}}}{4 \cdot s} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s) :precision binary32 (/ (exp (/ (- x_m) s)) (* 4.0 s)))

C

x_m = fabs(x);
float code(float x_m, float s) {
	return expf((-x_m / s)) / (4.0f * s);
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    code = exp((-x_m / s)) / (4.0e0 * s)
end function

Julia

x_m = abs(x)
function code(x_m, s)
	return Float32(exp(Float32(Float32(-x_m) / s)) / Float32(Float32(4.0) * s))
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	tmp = exp((-x_m / s)) / (single(4.0) * s);
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift-*.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. lift-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. +-commutative N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \color{blue}{\left(e^{\frac{-\left|x\right|}{s}} + 1\right)}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. distribute-lft-in N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s \cdot 1\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. *-rgt-identity N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + \color{blue}{s}\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. lower-+.f32 N/A

      \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(s \cdot e^{\frac{-\left|x\right|}{s}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

4. Applied rewrites 97.0%

   \[\leadsto \frac{e^{\frac{-\left|x\right|}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right)} \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
5. Step-by-step derivation

   1. lift-/.f32 N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{-\left|x\right|}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   2. frac-2neg N/A

      \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(\left(-\left|x\right|\right)\right)}{\mathsf{neg}\left(s\right)}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   3. lift-neg.f32 N/A

      \[\leadsto \frac{e^{\frac{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\left|x\right|\right)\right)}\right)}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   4. remove-double-neg N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   5. lift-fabs.f32 N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\left|x\right|}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   6. rem-sqrt-square-rev N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x \cdot x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   7. sqrt-prod N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{\sqrt{x} \cdot \sqrt{x}}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   8. rem-square-sqrt N/A

      \[\leadsto \frac{e^{\frac{\color{blue}{x}}{\mathsf{neg}\left(s\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   9. distribute-neg-frac2 N/A

      \[\leadsto \frac{e^{\color{blue}{\mathsf{neg}\left(\frac{x}{s}\right)}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   10. distribute-frac-neg N/A

       \[\leadsto \frac{e^{\color{blue}{\frac{\mathsf{neg}\left(x\right)}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   11. lift-neg.f32 N/A

       \[\leadsto \frac{e^{\frac{\color{blue}{-x}}{s}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   12. lift-/.f32 59.5

       \[\leadsto \frac{e^{\color{blue}{\frac{-x}{s}}}}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]

   13. lift-*.f32 N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(\frac{s}{e^{\frac{x}{s}}} + s\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)}} \]

   14. *-commutative N/A

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

   15. lower-*.f32 59.5

       \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{\left(1 + e^{\frac{-\left|x\right|}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

6. Applied rewrites 62.3%

   \[\leadsto \color{blue}{\frac{e^{\frac{-x}{s}}}{\left(1 + e^{\frac{-x}{s}}\right) \cdot \left(\frac{s}{e^{\frac{x}{s}}} + s\right)}} \]

7. Taylor expanded in x around 0

   \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{4 \cdot s}} \]
8. Step-by-step derivation

   1. lower-*.f32 58.7

      \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{4 \cdot s}} \]

9. Applied rewrites 58.7%

   \[\leadsto \frac{e^{\frac{-x}{s}}}{\color{blue}{4 \cdot s}} \]
10. Add Preprocessing

Alternative 14: 27.3% accurate, 31.1× speedup

Math

\[\begin{array}{l} x_m = \left|x\right| \\ \frac{0.25}{s} \end{array} \]

FPCore

x_m = (fabs.f32 x)
(FPCore (x_m s) :precision binary32 (/ 0.25 s))

C

x_m = fabs(x);
float code(float x_m, float s) {
	return 0.25f / s;
}

Fortran

x_m = abs(x)
real(4) function code(x_m, s)
    real(4), intent (in) :: x_m
    real(4), intent (in) :: s
    code = 0.25e0 / s
end function

Julia

x_m = abs(x)
function code(x_m, s)
	return Float32(Float32(0.25) / s)
end

MATLAB

x_m = abs(x);
function tmp = code(x_m, s)
	tmp = single(0.25) / s;
end

Derivation

1. Initial program 99.8%

   \[\frac{e^{\frac{-\left|x\right|}{s}}}{\left(s \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)\right) \cdot \left(1 + e^{\frac{-\left|x\right|}{s}}\right)} \]
2. Add Preprocessing

3. Taylor expanded in s around inf

   \[\leadsto \color{blue}{\frac{\frac{1}{4}}{s}} \]
4. Step-by-step derivation

   1. lower-/.f32 27.1

      \[\leadsto \color{blue}{\frac{0.25}{s}} \]

5. Applied rewrites 27.1%

   \[\leadsto \color{blue}{\frac{0.25}{s}} \]
6. Add Preprocessing

Reproduce

herbie shell --seed 2024339 
(FPCore (x s)
  :name "Logistic distribution"
  :precision binary32
  :pre (and (<= 0.0 s) (<= s 1.0651631))
  (/ (exp (/ (- (fabs x)) s)) (* (* s (+ 1.0 (exp (/ (- (fabs x)) s)))) (+ 1.0 (exp (/ (- (fabs x)) s))))))