expq2 (section 3.11)

Percentage Accurate: 36.8% → 100.0%

Time: 5.0s

Alternatives: 6

Speedup: 2.1×

Specification

\[710 > x\]

Math

\[\begin{array}{l} \\ \frac{e^{x}}{e^{x} - 1} \end{array} \]

FPCore

(FPCore (x) :precision binary64 (/ (exp x) (- (exp x) 1.0)))

C

double code(double x) {
	return exp(x) / (exp(x) - 1.0);
}

Fortran

module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x)
use fmin_fmax_functions
    real(8), intent (in) :: x
    code = exp(x) / (exp(x) - 1.0d0)
end function

Java

public static double code(double x) {
	return Math.exp(x) / (Math.exp(x) - 1.0);
}

Python

def code(x):
	return math.exp(x) / (math.exp(x) - 1.0)

Julia

function code(x)
	return Float64(exp(x) / Float64(exp(x) - 1.0))
end

MATLAB

function tmp = code(x)
	tmp = exp(x) / (exp(x) - 1.0);
end

Wolfram

code[x_] := N[(N[Exp[x], $MachinePrecision] / N[(N[Exp[x], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]

Initial Program: 36.8% accurate, 1.0× speedup

Math

\[\begin{array}{l} \\ \frac{e^{x}}{e^{x} - 1} \end{array} \]

FPCore

(FPCore (x) :precision binary64 (/ (exp x) (- (exp x) 1.0)))

C

double code(double x) {
	return exp(x) / (exp(x) - 1.0);
}

Fortran

module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x)
use fmin_fmax_functions
    real(8), intent (in) :: x
    code = exp(x) / (exp(x) - 1.0d0)
end function

Java

public static double code(double x) {
	return Math.exp(x) / (Math.exp(x) - 1.0);
}

Python

def code(x):
	return math.exp(x) / (math.exp(x) - 1.0)

Julia

function code(x)
	return Float64(exp(x) / Float64(exp(x) - 1.0))
end

MATLAB

function tmp = code(x)
	tmp = exp(x) / (exp(x) - 1.0);
end

Wolfram

code[x_] := N[(N[Exp[x], $MachinePrecision] / N[(N[Exp[x], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]

Alternative 1: 100.0% accurate, 1.0× speedup

Math

\[\begin{array}{l} \\ \frac{e^{x}}{\mathsf{expm1}\left(x\right)} \end{array} \]

FPCore

(FPCore (x) :precision binary64 (/ (exp x) (expm1 x)))

C

double code(double x) {
	return exp(x) / expm1(x);
}

Java

public static double code(double x) {
	return Math.exp(x) / Math.expm1(x);
}

Python

def code(x):
	return math.exp(x) / math.expm1(x)

Julia

function code(x)
	return Float64(exp(x) / expm1(x))
end

Wolfram

code[x_] := N[(N[Exp[x], $MachinePrecision] / N[(Exp[x] - 1), $MachinePrecision]), $MachinePrecision]

Derivation

1. Initial program 36.8%

   \[\frac{e^{x}}{e^{x} - 1} \]
2. Add Preprocessing
3. Step-by-step derivation

   1. lift--.f64 N/A

      \[\leadsto \frac{e^{x}}{\color{blue}{e^{x} - 1}} \]

   2. unpow1 N/A

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

   3. metadata-eval N/A

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

   4. sqrt-pow1 N/A

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

   5. pow2 N/A

      \[\leadsto \frac{e^{x}}{\sqrt{\color{blue}{e^{x} \cdot e^{x}}} - 1} \]

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

      \[\leadsto \frac{e^{x}}{\color{blue}{\left|e^{x}\right|} - 1} \]

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

      \[\leadsto \frac{e^{x}}{\color{blue}{\sqrt{e^{x} \cdot e^{x}}} - 1} \]

   8. pow2 N/A

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

   9. sqrt-pow1 N/A

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

   10. metadata-eval N/A

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

   11. unpow1 N/A

       \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

   12. lift-exp.f64 N/A

       \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

   13. lower-expm1.f64 100.0

       \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]

4. Applied rewrites 100.0%

   \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]
5. Add Preprocessing

Alternative 2: 99.3% accurate, 1.7× speedup

Math

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -3.9:\\ \;\;\;\;\frac{e^{x}}{\left(1 + x\right) - 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(0.08333333333333333, x, {x}^{-1}\right) - -0.5\\ \end{array} \end{array} \]

FPCore

(FPCore (x)
 :precision binary64
 (if (<= x -3.9)
   (/ (exp x) (- (+ 1.0 x) 1.0))
   (- (fma 0.08333333333333333 x (pow x -1.0)) -0.5)))

C

double code(double x) {
	double tmp;
	if (x <= -3.9) {
		tmp = exp(x) / ((1.0 + x) - 1.0);
	} else {
		tmp = fma(0.08333333333333333, x, pow(x, -1.0)) - -0.5;
	}
	return tmp;
}

Julia

function code(x)
	tmp = 0.0
	if (x <= -3.9)
		tmp = Float64(exp(x) / Float64(Float64(1.0 + x) - 1.0));
	else
		tmp = Float64(fma(0.08333333333333333, x, (x ^ -1.0)) - -0.5);
	end
	return tmp
end

Wolfram

code[x_] := If[LessEqual[x, -3.9], N[(N[Exp[x], $MachinePrecision] / N[(N[(1.0 + x), $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision], N[(N[(0.08333333333333333 * x + N[Power[x, -1.0], $MachinePrecision]), $MachinePrecision] - -0.5), $MachinePrecision]]

Derivation

1. Split input into 2 regimes

2. if x < -3.89999999999999991

   1. Initial program 100.0%

      \[\frac{e^{x}}{e^{x} - 1} \]
   2. Add Preprocessing

   3. Taylor expanded in x around 0

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

      1. lower-+.f64 99.0

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

   5. Applied rewrites 99.0%

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

   if -3.89999999999999991 < x

   1. Initial program 7.0%

      \[\frac{e^{x}}{e^{x} - 1} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift--.f64 N/A

         \[\leadsto \frac{e^{x}}{\color{blue}{e^{x} - 1}} \]

      2. unpow1 N/A

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

      3. metadata-eval N/A

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

      4. sqrt-pow1 N/A

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

      5. pow2 N/A

         \[\leadsto \frac{e^{x}}{\sqrt{\color{blue}{e^{x} \cdot e^{x}}} - 1} \]

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

         \[\leadsto \frac{e^{x}}{\color{blue}{\left|e^{x}\right|} - 1} \]

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

         \[\leadsto \frac{e^{x}}{\color{blue}{\sqrt{e^{x} \cdot e^{x}}} - 1} \]

      8. pow2 N/A

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

      9. sqrt-pow1 N/A

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

      10. metadata-eval N/A

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

      11. unpow1 N/A

          \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

      12. lift-exp.f64 N/A

          \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

      13. lower-expm1.f64 100.0

          \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]

   4. Applied rewrites 100.0%

      \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \color{blue}{\frac{1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{12} + \frac{-1}{720} \cdot {x}^{2}\right)\right)}{x}} \]

   7. Applied rewrites 98.7%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(x \cdot x, -0.001388888888888889, 0.08333333333333333\right), x, \frac{1}{x} - -0.5\right)} \]
   8. Step-by-step derivation

   9. Applied rewrites 98.7%

      \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(-0.001388888888888889, x \cdot x, 0.08333333333333333\right), x, {x}^{-1}\right) - \color{blue}{-0.5} \]

   10. Taylor expanded in x around 0

       \[\leadsto \frac{1 + \frac{1}{12} \cdot {x}^{2}}{x} - \frac{-1}{2} \]
   11. Step-by-step derivation

   12. Applied rewrites 98.7%

       \[\leadsto \mathsf{fma}\left(0.08333333333333333, x, \frac{1}{x}\right) - -0.5 \]
3. Recombined 2 regimes into one program.

4. Final simplification 98.8%

   \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -3.9:\\ \;\;\;\;\frac{e^{x}}{\left(1 + x\right) - 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(0.08333333333333333, x, {x}^{-1}\right) - -0.5\\ \end{array} \]
5. Add Preprocessing

Alternative 3: 84.1% accurate, 1.7× speedup

Math

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq -700:\\ \;\;\;\;\sqrt{{\left(x \cdot x\right)}^{-1}}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(0.08333333333333333, x, {x}^{-1}\right) - -0.5\\ \end{array} \end{array} \]

FPCore

(FPCore (x)
 :precision binary64
 (if (<= x -700.0)
   (sqrt (pow (* x x) -1.0))
   (- (fma 0.08333333333333333 x (pow x -1.0)) -0.5)))

C

double code(double x) {
	double tmp;
	if (x <= -700.0) {
		tmp = sqrt(pow((x * x), -1.0));
	} else {
		tmp = fma(0.08333333333333333, x, pow(x, -1.0)) - -0.5;
	}
	return tmp;
}

Julia

function code(x)
	tmp = 0.0
	if (x <= -700.0)
		tmp = sqrt((Float64(x * x) ^ -1.0));
	else
		tmp = Float64(fma(0.08333333333333333, x, (x ^ -1.0)) - -0.5);
	end
	return tmp
end

Wolfram

code[x_] := If[LessEqual[x, -700.0], N[Sqrt[N[Power[N[(x * x), $MachinePrecision], -1.0], $MachinePrecision]], $MachinePrecision], N[(N[(0.08333333333333333 * x + N[Power[x, -1.0], $MachinePrecision]), $MachinePrecision] - -0.5), $MachinePrecision]]

Derivation

1. Split input into 2 regimes

2. if x < -700

   1. Initial program 100.0%

      \[\frac{e^{x}}{e^{x} - 1} \]
   2. Add Preprocessing

   3. Taylor expanded in x around 0

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

      1. lower-/.f64 5.9

         \[\leadsto \color{blue}{\frac{1}{x}} \]

   5. Applied rewrites 5.9%

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

   7. Applied rewrites 51.3%

      \[\leadsto \sqrt{{x}^{-2}} \]
   8. Step-by-step derivation

   9. Applied rewrites 52.5%

      \[\leadsto \sqrt{\frac{1}{x \cdot x}} \]

   if -700 < x

   1. Initial program 7.5%

      \[\frac{e^{x}}{e^{x} - 1} \]
   2. Add Preprocessing
   3. Step-by-step derivation

      1. lift--.f64 N/A

         \[\leadsto \frac{e^{x}}{\color{blue}{e^{x} - 1}} \]

      2. unpow1 N/A

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

      3. metadata-eval N/A

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

      4. sqrt-pow1 N/A

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

      5. pow2 N/A

         \[\leadsto \frac{e^{x}}{\sqrt{\color{blue}{e^{x} \cdot e^{x}}} - 1} \]

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

         \[\leadsto \frac{e^{x}}{\color{blue}{\left|e^{x}\right|} - 1} \]

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

         \[\leadsto \frac{e^{x}}{\color{blue}{\sqrt{e^{x} \cdot e^{x}}} - 1} \]

      8. pow2 N/A

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

      9. sqrt-pow1 N/A

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

      10. metadata-eval N/A

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

      11. unpow1 N/A

          \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

      12. lift-exp.f64 N/A

          \[\leadsto \frac{e^{x}}{\color{blue}{e^{x}} - 1} \]

      13. lower-expm1.f64 100.0

          \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]

   4. Applied rewrites 100.0%

      \[\leadsto \frac{e^{x}}{\color{blue}{\mathsf{expm1}\left(x\right)}} \]

   5. Taylor expanded in x around 0

      \[\leadsto \color{blue}{\frac{1 + x \cdot \left(\frac{1}{2} + x \cdot \left(\frac{1}{12} + \frac{-1}{720} \cdot {x}^{2}\right)\right)}{x}} \]

   7. Applied rewrites 98.1%

      \[\leadsto \color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(x \cdot x, -0.001388888888888889, 0.08333333333333333\right), x, \frac{1}{x} - -0.5\right)} \]
   8. Step-by-step derivation

   9. Applied rewrites 98.1%

      \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(-0.001388888888888889, x \cdot x, 0.08333333333333333\right), x, {x}^{-1}\right) - \color{blue}{-0.5} \]

   10. Taylor expanded in x around 0

       \[\leadsto \frac{1 + \frac{1}{12} \cdot {x}^{2}}{x} - \frac{-1}{2} \]
   11. Step-by-step derivation

   12. Applied rewrites 98.2%

       \[\leadsto \mathsf{fma}\left(0.08333333333333333, x, \frac{1}{x}\right) - -0.5 \]
3. Recombined 2 regimes into one program.

4. Final simplification 83.7%

   \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -700:\\ \;\;\;\;\sqrt{{\left(x \cdot x\right)}^{-1}}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{fma}\left(0.08333333333333333, x, {x}^{-1}\right) - -0.5\\ \end{array} \]
5. Add Preprocessing

Alternative 4: 67.6% accurate, 2.1× speedup

Math

\[\begin{array}{l} \\ {x}^{-1} \end{array} \]

FPCore

(FPCore (x) :precision binary64 (pow x -1.0))

C

double code(double x) {
	return pow(x, -1.0);
}

Fortran

module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x)
use fmin_fmax_functions
    real(8), intent (in) :: x
    code = x ** (-1.0d0)
end function

Java

public static double code(double x) {
	return Math.pow(x, -1.0);
}

Python

def code(x):
	return math.pow(x, -1.0)

Julia

function code(x)
	return x ^ -1.0
end

MATLAB

function tmp = code(x)
	tmp = x ^ -1.0;
end

Wolfram

code[x_] := N[Power[x, -1.0], $MachinePrecision]

Derivation

1. Initial program 36.8%

   \[\frac{e^{x}}{e^{x} - 1} \]
2. Add Preprocessing

3. Taylor expanded in x around 0

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

   1. lower-/.f64 67.9

      \[\leadsto \color{blue}{\frac{1}{x}} \]

5. Applied rewrites 67.9%

   \[\leadsto \color{blue}{\frac{1}{x}} \]

6. Final simplification 67.9%

   \[\leadsto {x}^{-1} \]
7. Add Preprocessing

Alternative 5: 3.3% accurate, 35.8× speedup

Math

\[\begin{array}{l} \\ 0.08333333333333333 \cdot x \end{array} \]

FPCore

(FPCore (x) :precision binary64 (* 0.08333333333333333 x))

C

double code(double x) {
	return 0.08333333333333333 * x;
}

Fortran

module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x)
use fmin_fmax_functions
    real(8), intent (in) :: x
    code = 0.08333333333333333d0 * x
end function

Java

public static double code(double x) {
	return 0.08333333333333333 * x;
}

Python

def code(x):
	return 0.08333333333333333 * x

Julia

function code(x)
	return Float64(0.08333333333333333 * x)
end

MATLAB

function tmp = code(x)
	tmp = 0.08333333333333333 * x;
end

Wolfram

code[x_] := N[(0.08333333333333333 * x), $MachinePrecision]

Derivation

1. Initial program 36.8%

   \[\frac{e^{x}}{e^{x} - 1} \]
2. Add Preprocessing

3. Taylor expanded in x around 0

   \[\leadsto \color{blue}{\frac{1 + x \cdot \left(\frac{1}{2} + \frac{1}{12} \cdot x\right)}{x}} \]
4. Step-by-step derivation

   1. distribute-lft-in N/A

      \[\leadsto \frac{1 + \color{blue}{\left(x \cdot \frac{1}{2} + x \cdot \left(\frac{1}{12} \cdot x\right)\right)}}{x} \]

   2. *-commutative N/A

      \[\leadsto \frac{1 + \left(\color{blue}{\frac{1}{2} \cdot x} + x \cdot \left(\frac{1}{12} \cdot x\right)\right)}{x} \]

   3. associate-+r+ N/A

      \[\leadsto \frac{\color{blue}{\left(1 + \frac{1}{2} \cdot x\right) + x \cdot \left(\frac{1}{12} \cdot x\right)}}{x} \]

   4. div-add N/A

      \[\leadsto \color{blue}{\frac{1 + \frac{1}{2} \cdot x}{x} + \frac{x \cdot \left(\frac{1}{12} \cdot x\right)}{x}} \]

   5. *-commutative N/A

      \[\leadsto \frac{1 + \frac{1}{2} \cdot x}{x} + \frac{\color{blue}{\left(\frac{1}{12} \cdot x\right) \cdot x}}{x} \]

   6. associate-/l* N/A

      \[\leadsto \frac{1 + \frac{1}{2} \cdot x}{x} + \color{blue}{\left(\frac{1}{12} \cdot x\right) \cdot \frac{x}{x}} \]

   7. *-inverses N/A

      \[\leadsto \frac{1 + \frac{1}{2} \cdot x}{x} + \left(\frac{1}{12} \cdot x\right) \cdot \color{blue}{1} \]

   8. *-rgt-identity N/A

      \[\leadsto \frac{1 + \frac{1}{2} \cdot x}{x} + \color{blue}{\frac{1}{12} \cdot x} \]

   9. +-commutative N/A

      \[\leadsto \color{blue}{\frac{1}{12} \cdot x + \frac{1 + \frac{1}{2} \cdot x}{x}} \]

   10. lower-fma.f64 N/A

       \[\leadsto \color{blue}{\mathsf{fma}\left(\frac{1}{12}, x, \frac{1 + \frac{1}{2} \cdot x}{x}\right)} \]

   11. *-commutative N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1 + \color{blue}{x \cdot \frac{1}{2}}}{x}\right) \]

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

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{\color{blue}{1 - \left(\mathsf{neg}\left(x\right)\right) \cdot \frac{1}{2}}}{x}\right) \]

   13. div-sub N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \color{blue}{\frac{1}{x} - \frac{\left(\mathsf{neg}\left(x\right)\right) \cdot \frac{1}{2}}{x}}\right) \]

   14. associate-*r/ N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \color{blue}{\left(\mathsf{neg}\left(x\right)\right) \cdot \frac{\frac{1}{2}}{x}}\right) \]

   15. distribute-lft-neg-out N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \color{blue}{\left(\mathsf{neg}\left(x \cdot \frac{\frac{1}{2}}{x}\right)\right)}\right) \]

   16. associate-/l* N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\color{blue}{\frac{x \cdot \frac{1}{2}}{x}}\right)\right)\right) \]

   17. *-commutative N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\frac{\color{blue}{\frac{1}{2} \cdot x}}{x}\right)\right)\right) \]

   18. *-commutative N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\frac{\color{blue}{x \cdot \frac{1}{2}}}{x}\right)\right)\right) \]

   19. *-rgt-identity N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\frac{x \cdot \frac{1}{2}}{\color{blue}{x \cdot 1}}\right)\right)\right) \]

   20. times-frac N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\color{blue}{\frac{x}{x} \cdot \frac{\frac{1}{2}}{1}}\right)\right)\right) \]

   21. *-inverses N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\color{blue}{1} \cdot \frac{\frac{1}{2}}{1}\right)\right)\right) \]

   22. metadata-eval N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(1 \cdot \color{blue}{\frac{1}{2}}\right)\right)\right) \]

   23. metadata-eval N/A

       \[\leadsto \mathsf{fma}\left(\frac{1}{12}, x, \frac{1}{x} - \left(\mathsf{neg}\left(\color{blue}{\frac{1}{2}}\right)\right)\right) \]

5. Applied rewrites 67.8%

   \[\leadsto \color{blue}{\mathsf{fma}\left(0.08333333333333333, x, \frac{1}{x} - -0.5\right)} \]

6. Taylor expanded in x around inf

   \[\leadsto \frac{1}{12} \cdot \color{blue}{x} \]
7. Step-by-step derivation

8. Applied rewrites 3.5%

   \[\leadsto 0.08333333333333333 \cdot \color{blue}{x} \]
9. Add Preprocessing

Alternative 6: 3.2% accurate, 215.0× speedup

Math

\[\begin{array}{l} \\ 0.5 \end{array} \]

FPCore

(FPCore (x) :precision binary64 0.5)

C

double code(double x) {
	return 0.5;
}

Fortran

module fmin_fmax_functions
    implicit none
    private
    public fmax
    public fmin

    interface fmax
        module procedure fmax88
        module procedure fmax44
        module procedure fmax84
        module procedure fmax48
    end interface
    interface fmin
        module procedure fmin88
        module procedure fmin44
        module procedure fmin84
        module procedure fmin48
    end interface
contains
    real(8) function fmax88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(4) function fmax44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, max(x, y), y /= y), x /= x)
    end function
    real(8) function fmax84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, max(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmax48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), max(dble(x), y), y /= y), x /= x)
    end function
    real(8) function fmin88(x, y) result (res)
        real(8), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(4) function fmin44(x, y) result (res)
        real(4), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(y, merge(x, min(x, y), y /= y), x /= x)
    end function
    real(8) function fmin84(x, y) result(res)
        real(8), intent (in) :: x
        real(4), intent (in) :: y
        res = merge(dble(y), merge(x, min(x, dble(y)), y /= y), x /= x)
    end function
    real(8) function fmin48(x, y) result(res)
        real(4), intent (in) :: x
        real(8), intent (in) :: y
        res = merge(y, merge(dble(x), min(dble(x), y), y /= y), x /= x)
    end function
end module

real(8) function code(x)
use fmin_fmax_functions
    real(8), intent (in) :: x
    code = 0.5d0
end function

Java

public static double code(double x) {
	return 0.5;
}

Python

def code(x):
	return 0.5

Julia

function code(x)
	return 0.5
end

MATLAB

function tmp = code(x)
	tmp = 0.5;
end

Wolfram

code[x_] := 0.5

Derivation

1. Initial program 36.8%

   \[\frac{e^{x}}{e^{x} - 1} \]
2. Add Preprocessing

3. Taylor expanded in x around 0

   \[\leadsto \color{blue}{\frac{1 + \frac{1}{2} \cdot x}{x}} \]
4. Step-by-step derivation

   1. *-commutative N/A

      \[\leadsto \frac{1 + \color{blue}{x \cdot \frac{1}{2}}}{x} \]

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

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

   3. div-sub N/A

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

   4. associate-*r/ N/A

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

   5. distribute-lft-neg-out N/A

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

   6. associate-/l* N/A

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

   7. *-commutative N/A

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

   8. *-commutative N/A

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

   9. *-rgt-identity N/A

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

   10. times-frac N/A

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

   11. *-inverses N/A

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

   12. metadata-eval N/A

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

   13. metadata-eval N/A

       \[\leadsto \frac{1}{x} - \left(\mathsf{neg}\left(\color{blue}{\frac{1}{2}}\right)\right) \]

   14. lower--.f64 N/A

       \[\leadsto \color{blue}{\frac{1}{x} - \left(\mathsf{neg}\left(\frac{1}{2}\right)\right)} \]

   15. lower-/.f64 N/A

       \[\leadsto \color{blue}{\frac{1}{x}} - \left(\mathsf{neg}\left(\frac{1}{2}\right)\right) \]

   16. metadata-eval 67.8

       \[\leadsto \frac{1}{x} - \color{blue}{-0.5} \]

5. Applied rewrites 67.8%

   \[\leadsto \color{blue}{\frac{1}{x} - -0.5} \]

6. Taylor expanded in x around inf

   \[\leadsto \frac{1}{2} \]
7. Step-by-step derivation

8. Applied rewrites 3.2%

   \[\leadsto 0.5 \]
9. Add Preprocessing

Developer Target 1: 100.0% accurate, 1.9× speedup

Math

\[\begin{array}{l} \\ \frac{-1}{\mathsf{expm1}\left(-x\right)} \end{array} \]

FPCore

(FPCore (x) :precision binary64 (/ (- 1.0) (expm1 (- x))))

C

double code(double x) {
	return -1.0 / expm1(-x);
}

Java

public static double code(double x) {
	return -1.0 / Math.expm1(-x);
}

Python

def code(x):
	return -1.0 / math.expm1(-x)

Julia

function code(x)
	return Float64(Float64(-1.0) / expm1(Float64(-x)))
end

Wolfram

code[x_] := N[((-1.0) / N[(Exp[(-x)] - 1), $MachinePrecision]), $MachinePrecision]

Reproduce

herbie shell --seed 2024350 
(FPCore (x)
  :name "expq2 (section 3.11)"
  :precision binary64
  :pre (> 710.0 x)

  :alt
  (! :herbie-platform default (/ (- 1) (expm1 (- x))))

  (/ (exp x) (- (exp x) 1.0)))