Harley's example

Percentage Accurate: 90.7% → 99.5%
Time: 54.5s
Alternatives: 5
Speedup: 896.0×

Specification

?
\[0 < c\_p \land 0 < c\_n\]
\[\begin{array}{l} \\ \begin{array}{l} t_1 := \frac{1}{1 + e^{-t}}\\ t_2 := \frac{1}{1 + e^{-s}}\\ \frac{{t\_2}^{c\_p} \cdot {\left(1 - t\_2\right)}^{c\_n}}{{t\_1}^{c\_p} \cdot {\left(1 - t\_1\right)}^{c\_n}} \end{array} \end{array} \]
(FPCore (c_p c_n t s)
 :precision binary64
 (let* ((t_1 (/ 1.0 (+ 1.0 (exp (- t))))) (t_2 (/ 1.0 (+ 1.0 (exp (- s))))))
   (/
    (* (pow t_2 c_p) (pow (- 1.0 t_2) c_n))
    (* (pow t_1 c_p) (pow (- 1.0 t_1) c_n)))))
double code(double c_p, double c_n, double t, double s) {
	double t_1 = 1.0 / (1.0 + exp(-t));
	double t_2 = 1.0 / (1.0 + exp(-s));
	return (pow(t_2, c_p) * pow((1.0 - t_2), c_n)) / (pow(t_1, c_p) * pow((1.0 - t_1), c_n));
}
real(8) function code(c_p, c_n, t, s)
    real(8), intent (in) :: c_p
    real(8), intent (in) :: c_n
    real(8), intent (in) :: t
    real(8), intent (in) :: s
    real(8) :: t_1
    real(8) :: t_2
    t_1 = 1.0d0 / (1.0d0 + exp(-t))
    t_2 = 1.0d0 / (1.0d0 + exp(-s))
    code = ((t_2 ** c_p) * ((1.0d0 - t_2) ** c_n)) / ((t_1 ** c_p) * ((1.0d0 - t_1) ** c_n))
end function
public static double code(double c_p, double c_n, double t, double s) {
	double t_1 = 1.0 / (1.0 + Math.exp(-t));
	double t_2 = 1.0 / (1.0 + Math.exp(-s));
	return (Math.pow(t_2, c_p) * Math.pow((1.0 - t_2), c_n)) / (Math.pow(t_1, c_p) * Math.pow((1.0 - t_1), c_n));
}
def code(c_p, c_n, t, s):
	t_1 = 1.0 / (1.0 + math.exp(-t))
	t_2 = 1.0 / (1.0 + math.exp(-s))
	return (math.pow(t_2, c_p) * math.pow((1.0 - t_2), c_n)) / (math.pow(t_1, c_p) * math.pow((1.0 - t_1), c_n))
function code(c_p, c_n, t, s)
	t_1 = Float64(1.0 / Float64(1.0 + exp(Float64(-t))))
	t_2 = Float64(1.0 / Float64(1.0 + exp(Float64(-s))))
	return Float64(Float64((t_2 ^ c_p) * (Float64(1.0 - t_2) ^ c_n)) / Float64((t_1 ^ c_p) * (Float64(1.0 - t_1) ^ c_n)))
end
function tmp = code(c_p, c_n, t, s)
	t_1 = 1.0 / (1.0 + exp(-t));
	t_2 = 1.0 / (1.0 + exp(-s));
	tmp = ((t_2 ^ c_p) * ((1.0 - t_2) ^ c_n)) / ((t_1 ^ c_p) * ((1.0 - t_1) ^ c_n));
end
code[c$95$p_, c$95$n_, t_, s_] := Block[{t$95$1 = N[(1.0 / N[(1.0 + N[Exp[(-t)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(1.0 / N[(1.0 + N[Exp[(-s)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, N[(N[(N[Power[t$95$2, c$95$p], $MachinePrecision] * N[Power[N[(1.0 - t$95$2), $MachinePrecision], c$95$n], $MachinePrecision]), $MachinePrecision] / N[(N[Power[t$95$1, c$95$p], $MachinePrecision] * N[Power[N[(1.0 - t$95$1), $MachinePrecision], c$95$n], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \frac{1}{1 + e^{-t}}\\
t_2 := \frac{1}{1 + e^{-s}}\\
\frac{{t\_2}^{c\_p} \cdot {\left(1 - t\_2\right)}^{c\_n}}{{t\_1}^{c\_p} \cdot {\left(1 - t\_1\right)}^{c\_n}}
\end{array}
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 5 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 90.7% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_1 := \frac{1}{1 + e^{-t}}\\ t_2 := \frac{1}{1 + e^{-s}}\\ \frac{{t\_2}^{c\_p} \cdot {\left(1 - t\_2\right)}^{c\_n}}{{t\_1}^{c\_p} \cdot {\left(1 - t\_1\right)}^{c\_n}} \end{array} \end{array} \]
(FPCore (c_p c_n t s)
 :precision binary64
 (let* ((t_1 (/ 1.0 (+ 1.0 (exp (- t))))) (t_2 (/ 1.0 (+ 1.0 (exp (- s))))))
   (/
    (* (pow t_2 c_p) (pow (- 1.0 t_2) c_n))
    (* (pow t_1 c_p) (pow (- 1.0 t_1) c_n)))))
double code(double c_p, double c_n, double t, double s) {
	double t_1 = 1.0 / (1.0 + exp(-t));
	double t_2 = 1.0 / (1.0 + exp(-s));
	return (pow(t_2, c_p) * pow((1.0 - t_2), c_n)) / (pow(t_1, c_p) * pow((1.0 - t_1), c_n));
}
real(8) function code(c_p, c_n, t, s)
    real(8), intent (in) :: c_p
    real(8), intent (in) :: c_n
    real(8), intent (in) :: t
    real(8), intent (in) :: s
    real(8) :: t_1
    real(8) :: t_2
    t_1 = 1.0d0 / (1.0d0 + exp(-t))
    t_2 = 1.0d0 / (1.0d0 + exp(-s))
    code = ((t_2 ** c_p) * ((1.0d0 - t_2) ** c_n)) / ((t_1 ** c_p) * ((1.0d0 - t_1) ** c_n))
end function
public static double code(double c_p, double c_n, double t, double s) {
	double t_1 = 1.0 / (1.0 + Math.exp(-t));
	double t_2 = 1.0 / (1.0 + Math.exp(-s));
	return (Math.pow(t_2, c_p) * Math.pow((1.0 - t_2), c_n)) / (Math.pow(t_1, c_p) * Math.pow((1.0 - t_1), c_n));
}
def code(c_p, c_n, t, s):
	t_1 = 1.0 / (1.0 + math.exp(-t))
	t_2 = 1.0 / (1.0 + math.exp(-s))
	return (math.pow(t_2, c_p) * math.pow((1.0 - t_2), c_n)) / (math.pow(t_1, c_p) * math.pow((1.0 - t_1), c_n))
function code(c_p, c_n, t, s)
	t_1 = Float64(1.0 / Float64(1.0 + exp(Float64(-t))))
	t_2 = Float64(1.0 / Float64(1.0 + exp(Float64(-s))))
	return Float64(Float64((t_2 ^ c_p) * (Float64(1.0 - t_2) ^ c_n)) / Float64((t_1 ^ c_p) * (Float64(1.0 - t_1) ^ c_n)))
end
function tmp = code(c_p, c_n, t, s)
	t_1 = 1.0 / (1.0 + exp(-t));
	t_2 = 1.0 / (1.0 + exp(-s));
	tmp = ((t_2 ^ c_p) * ((1.0 - t_2) ^ c_n)) / ((t_1 ^ c_p) * ((1.0 - t_1) ^ c_n));
end
code[c$95$p_, c$95$n_, t_, s_] := Block[{t$95$1 = N[(1.0 / N[(1.0 + N[Exp[(-t)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(1.0 / N[(1.0 + N[Exp[(-s)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, N[(N[(N[Power[t$95$2, c$95$p], $MachinePrecision] * N[Power[N[(1.0 - t$95$2), $MachinePrecision], c$95$n], $MachinePrecision]), $MachinePrecision] / N[(N[Power[t$95$1, c$95$p], $MachinePrecision] * N[Power[N[(1.0 - t$95$1), $MachinePrecision], c$95$n], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}

\\
\begin{array}{l}
t_1 := \frac{1}{1 + e^{-t}}\\
t_2 := \frac{1}{1 + e^{-s}}\\
\frac{{t\_2}^{c\_p} \cdot {\left(1 - t\_2\right)}^{c\_n}}{{t\_1}^{c\_p} \cdot {\left(1 - t\_1\right)}^{c\_n}}
\end{array}
\end{array}

Alternative 1: 99.5% accurate, 6.7× speedup?

\[\begin{array}{l} \\ e^{\mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_p, 0.5 \cdot c\_n\right), t, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)} \end{array} \]
(FPCore (c_p c_n t s)
 :precision binary64
 (exp (fma (fma -0.5 c_p (* 0.5 c_n)) t (* (fma -0.5 c_n (* 0.5 c_p)) s))))
double code(double c_p, double c_n, double t, double s) {
	return exp(fma(fma(-0.5, c_p, (0.5 * c_n)), t, (fma(-0.5, c_n, (0.5 * c_p)) * s)));
}
function code(c_p, c_n, t, s)
	return exp(fma(fma(-0.5, c_p, Float64(0.5 * c_n)), t, Float64(fma(-0.5, c_n, Float64(0.5 * c_p)) * s)))
end
code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(N[(-0.5 * c$95$p + N[(0.5 * c$95$n), $MachinePrecision]), $MachinePrecision] * t + N[(N[(-0.5 * c$95$n + N[(0.5 * c$95$p), $MachinePrecision]), $MachinePrecision] * s), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
e^{\mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_p, 0.5 \cdot c\_n\right), t, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)}
\end{array}
Derivation
  1. Initial program 90.2%

    \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
  2. Add Preprocessing
  3. Applied rewrites96.1%

    \[\leadsto \color{blue}{e^{\mathsf{fma}\left(c\_p, \left(-\mathsf{log1p}\left(e^{-s}\right)\right) - \left(-\mathsf{log1p}\left(e^{-t}\right)\right), c\_n \cdot \left(\mathsf{log1p}\left(\frac{-1}{e^{-s} + 1}\right) - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right)\right)\right)}} \]
  4. Taylor expanded in s around 0

    \[\leadsto e^{\color{blue}{c\_n \cdot \left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
  5. Step-by-step derivation
    1. *-commutativeN/A

      \[\leadsto e^{\color{blue}{\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) \cdot c\_n} + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)} \]
    2. lower-fma.f64N/A

      \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right), c\_n, c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
  6. Applied rewrites97.2%

    \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log 0.5 - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right), c\_n, \mathsf{fma}\left(\mathsf{log1p}\left(e^{-t}\right) - \log 2, c\_p, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)\right)}} \]
  7. Taylor expanded in t around 0

    \[\leadsto e^{s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right) + \color{blue}{t \cdot \left(\frac{-1}{2} \cdot c\_p + \frac{1}{2} \cdot c\_n\right)}} \]
  8. Step-by-step derivation
    1. Applied rewrites98.7%

      \[\leadsto e^{\mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_p, 0.5 \cdot c\_n\right), \color{blue}{t}, \mathsf{fma}\left(-0.5, c\_n, c\_p \cdot 0.5\right) \cdot s\right)} \]
    2. Final simplification98.7%

      \[\leadsto e^{\mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_p, 0.5 \cdot c\_n\right), t, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)} \]
    3. Add Preprocessing

    Alternative 2: 98.5% accurate, 7.7× speedup?

    \[\begin{array}{l} \\ e^{\mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s} \end{array} \]
    (FPCore (c_p c_n t s)
     :precision binary64
     (exp (* (fma -0.5 c_n (* 0.5 c_p)) s)))
    double code(double c_p, double c_n, double t, double s) {
    	return exp((fma(-0.5, c_n, (0.5 * c_p)) * s));
    }
    
    function code(c_p, c_n, t, s)
    	return exp(Float64(fma(-0.5, c_n, Float64(0.5 * c_p)) * s))
    end
    
    code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(N[(-0.5 * c$95$n + N[(0.5 * c$95$p), $MachinePrecision]), $MachinePrecision] * s), $MachinePrecision]], $MachinePrecision]
    
    \begin{array}{l}
    
    \\
    e^{\mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s}
    \end{array}
    
    Derivation
    1. Initial program 90.2%

      \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
    2. Add Preprocessing
    3. Applied rewrites96.1%

      \[\leadsto \color{blue}{e^{\mathsf{fma}\left(c\_p, \left(-\mathsf{log1p}\left(e^{-s}\right)\right) - \left(-\mathsf{log1p}\left(e^{-t}\right)\right), c\_n \cdot \left(\mathsf{log1p}\left(\frac{-1}{e^{-s} + 1}\right) - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right)\right)\right)}} \]
    4. Taylor expanded in s around 0

      \[\leadsto e^{\color{blue}{c\_n \cdot \left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
    5. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto e^{\color{blue}{\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) \cdot c\_n} + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)} \]
      2. lower-fma.f64N/A

        \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right), c\_n, c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
    6. Applied rewrites97.2%

      \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log 0.5 - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right), c\_n, \mathsf{fma}\left(\mathsf{log1p}\left(e^{-t}\right) - \log 2, c\_p, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)\right)}} \]
    7. Taylor expanded in s around inf

      \[\leadsto e^{s \cdot \color{blue}{\left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)}} \]
    8. Step-by-step derivation
      1. Applied rewrites98.1%

        \[\leadsto e^{\mathsf{fma}\left(-0.5, c\_n, c\_p \cdot 0.5\right) \cdot \color{blue}{s}} \]
      2. Final simplification98.1%

        \[\leadsto e^{\mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s} \]
      3. Add Preprocessing

      Alternative 3: 96.5% accurate, 7.7× speedup?

      \[\begin{array}{l} \\ e^{\mathsf{fma}\left(-0.5, t, 0.5 \cdot s\right) \cdot c\_p} \end{array} \]
      (FPCore (c_p c_n t s) :precision binary64 (exp (* (fma -0.5 t (* 0.5 s)) c_p)))
      double code(double c_p, double c_n, double t, double s) {
      	return exp((fma(-0.5, t, (0.5 * s)) * c_p));
      }
      
      function code(c_p, c_n, t, s)
      	return exp(Float64(fma(-0.5, t, Float64(0.5 * s)) * c_p))
      end
      
      code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(N[(-0.5 * t + N[(0.5 * s), $MachinePrecision]), $MachinePrecision] * c$95$p), $MachinePrecision]], $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      e^{\mathsf{fma}\left(-0.5, t, 0.5 \cdot s\right) \cdot c\_p}
      \end{array}
      
      Derivation
      1. Initial program 90.2%

        \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
      2. Add Preprocessing
      3. Applied rewrites96.1%

        \[\leadsto \color{blue}{e^{\mathsf{fma}\left(c\_p, \left(-\mathsf{log1p}\left(e^{-s}\right)\right) - \left(-\mathsf{log1p}\left(e^{-t}\right)\right), c\_n \cdot \left(\mathsf{log1p}\left(\frac{-1}{e^{-s} + 1}\right) - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right)\right)\right)}} \]
      4. Taylor expanded in s around 0

        \[\leadsto e^{\color{blue}{c\_n \cdot \left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
      5. Step-by-step derivation
        1. *-commutativeN/A

          \[\leadsto e^{\color{blue}{\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)\right) \cdot c\_n} + \left(c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)} \]
        2. lower-fma.f64N/A

          \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log \frac{1}{2} - \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right), c\_n, c\_p \cdot \left(\log \left(1 + e^{\mathsf{neg}\left(t\right)}\right) - \log 2\right) + s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)\right)}} \]
      6. Applied rewrites97.2%

        \[\leadsto e^{\color{blue}{\mathsf{fma}\left(\log 0.5 - \mathsf{log1p}\left(\frac{-1}{e^{-t} + 1}\right), c\_n, \mathsf{fma}\left(\mathsf{log1p}\left(e^{-t}\right) - \log 2, c\_p, \mathsf{fma}\left(-0.5, c\_n, 0.5 \cdot c\_p\right) \cdot s\right)\right)}} \]
      7. Taylor expanded in t around 0

        \[\leadsto e^{s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right) + \color{blue}{t \cdot \left(\frac{-1}{2} \cdot c\_p + \frac{1}{2} \cdot c\_n\right)}} \]
      8. Step-by-step derivation
        1. Applied rewrites98.7%

          \[\leadsto e^{\mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_p, 0.5 \cdot c\_n\right), \color{blue}{t}, \mathsf{fma}\left(-0.5, c\_n, c\_p \cdot 0.5\right) \cdot s\right)} \]
        2. Taylor expanded in c_p around inf

          \[\leadsto e^{c\_p \cdot \left(\frac{-1}{2} \cdot t + \color{blue}{\frac{1}{2} \cdot s}\right)} \]
        3. Step-by-step derivation
          1. Applied rewrites94.1%

            \[\leadsto e^{\mathsf{fma}\left(-0.5, t, s \cdot 0.5\right) \cdot c\_p} \]
          2. Final simplification94.1%

            \[\leadsto e^{\mathsf{fma}\left(-0.5, t, 0.5 \cdot s\right) \cdot c\_p} \]
          3. Add Preprocessing

          Alternative 4: 93.7% accurate, 74.7× speedup?

          \[\begin{array}{l} \\ \mathsf{fma}\left(-0.5 \cdot c\_n, s, 1\right) \end{array} \]
          (FPCore (c_p c_n t s) :precision binary64 (fma (* -0.5 c_n) s 1.0))
          double code(double c_p, double c_n, double t, double s) {
          	return fma((-0.5 * c_n), s, 1.0);
          }
          
          function code(c_p, c_n, t, s)
          	return fma(Float64(-0.5 * c_n), s, 1.0)
          end
          
          code[c$95$p_, c$95$n_, t_, s_] := N[(N[(-0.5 * c$95$n), $MachinePrecision] * s + 1.0), $MachinePrecision]
          
          \begin{array}{l}
          
          \\
          \mathsf{fma}\left(-0.5 \cdot c\_n, s, 1\right)
          \end{array}
          
          Derivation
          1. Initial program 90.2%

            \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
          2. Add Preprocessing
          3. Taylor expanded in c_n around 0

            \[\leadsto \color{blue}{\frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
          4. Step-by-step derivation
            1. lower-/.f64N/A

              \[\leadsto \color{blue}{\frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
            2. lower-pow.f64N/A

              \[\leadsto \frac{\color{blue}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            3. lower-/.f64N/A

              \[\leadsto \frac{{\color{blue}{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            4. +-commutativeN/A

              \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            5. lower-+.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            6. lower-exp.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            7. lower-neg.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\color{blue}{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
            8. lower-pow.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{\color{blue}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
            9. lower-/.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\color{blue}{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}}^{c\_p}} \]
            10. +-commutativeN/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)} + 1}}\right)}^{c\_p}} \]
            11. lower-+.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)} + 1}}\right)}^{c\_p}} \]
            12. lower-exp.f64N/A

              \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)}} + 1}\right)}^{c\_p}} \]
            13. lower-neg.f6491.4

              \[\leadsto \frac{{\left(\frac{1}{e^{-s} + 1}\right)}^{c\_p}}{{\left(\frac{1}{e^{\color{blue}{-t}} + 1}\right)}^{c\_p}} \]
          5. Applied rewrites91.4%

            \[\leadsto \color{blue}{\frac{{\left(\frac{1}{e^{-s} + 1}\right)}^{c\_p}}{{\left(\frac{1}{e^{-t} + 1}\right)}^{c\_p}}} \]
          6. Taylor expanded in t around 0

            \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n} \cdot {\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}}} \]
          7. Step-by-step derivation
            1. associate-/l*N/A

              \[\leadsto \color{blue}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}}} \]
            2. lower-*.f64N/A

              \[\leadsto \color{blue}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}}} \]
            3. lower-pow.f64N/A

              \[\leadsto \color{blue}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n}} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            4. lower--.f64N/A

              \[\leadsto {\color{blue}{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            5. lower-/.f64N/A

              \[\leadsto {\left(1 - \color{blue}{\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            6. +-commutativeN/A

              \[\leadsto {\left(1 - \frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            7. lower-+.f64N/A

              \[\leadsto {\left(1 - \frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            8. lower-exp.f64N/A

              \[\leadsto {\left(1 - \frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            9. lower-neg.f64N/A

              \[\leadsto {\left(1 - \frac{1}{e^{\color{blue}{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}} \]
            10. lower-/.f64N/A

              \[\leadsto {\left(1 - \frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_n} \cdot \color{blue}{\frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\frac{1}{2}}^{c\_n} \cdot {\frac{1}{2}}^{c\_p}}} \]
          8. Applied rewrites90.7%

            \[\leadsto \color{blue}{{\left(1 - \frac{1}{e^{-s} + 1}\right)}^{c\_n} \cdot \frac{{\left(\frac{1}{e^{-s} + 1}\right)}^{c\_p}}{{0.5}^{c\_n} \cdot {0.5}^{c\_p}}} \]
          9. Taylor expanded in s around 0

            \[\leadsto 1 + \color{blue}{s \cdot \left(\frac{-1}{2} \cdot c\_n + \frac{1}{2} \cdot c\_p\right)} \]
          10. Step-by-step derivation
            1. Applied rewrites91.4%

              \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(-0.5, c\_n, c\_p \cdot 0.5\right), \color{blue}{s}, 1\right) \]
            2. Taylor expanded in c_n around inf

              \[\leadsto \mathsf{fma}\left(\frac{-1}{2} \cdot c\_n, s, 1\right) \]
            3. Step-by-step derivation
              1. Applied rewrites91.5%

                \[\leadsto \mathsf{fma}\left(-0.5 \cdot c\_n, s, 1\right) \]
              2. Add Preprocessing

              Alternative 5: 93.8% accurate, 896.0× speedup?

              \[\begin{array}{l} \\ 1 \end{array} \]
              (FPCore (c_p c_n t s) :precision binary64 1.0)
              double code(double c_p, double c_n, double t, double s) {
              	return 1.0;
              }
              
              real(8) function code(c_p, c_n, t, s)
                  real(8), intent (in) :: c_p
                  real(8), intent (in) :: c_n
                  real(8), intent (in) :: t
                  real(8), intent (in) :: s
                  code = 1.0d0
              end function
              
              public static double code(double c_p, double c_n, double t, double s) {
              	return 1.0;
              }
              
              def code(c_p, c_n, t, s):
              	return 1.0
              
              function code(c_p, c_n, t, s)
              	return 1.0
              end
              
              function tmp = code(c_p, c_n, t, s)
              	tmp = 1.0;
              end
              
              code[c$95$p_, c$95$n_, t_, s_] := 1.0
              
              \begin{array}{l}
              
              \\
              1
              \end{array}
              
              Derivation
              1. Initial program 90.2%

                \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
              2. Add Preprocessing
              3. Taylor expanded in c_n around 0

                \[\leadsto \color{blue}{\frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
              4. Step-by-step derivation
                1. lower-/.f64N/A

                  \[\leadsto \color{blue}{\frac{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
                2. lower-pow.f64N/A

                  \[\leadsto \frac{\color{blue}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_p}}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                3. lower-/.f64N/A

                  \[\leadsto \frac{{\color{blue}{\left(\frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                4. +-commutativeN/A

                  \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                5. lower-+.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)} + 1}}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                6. lower-exp.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                7. lower-neg.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\color{blue}{\mathsf{neg}\left(s\right)}} + 1}\right)}^{c\_p}}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}} \]
                8. lower-pow.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{\color{blue}{{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_p}}} \]
                9. lower-/.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\color{blue}{\left(\frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}}^{c\_p}} \]
                10. +-commutativeN/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)} + 1}}\right)}^{c\_p}} \]
                11. lower-+.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)} + 1}}\right)}^{c\_p}} \]
                12. lower-exp.f64N/A

                  \[\leadsto \frac{{\left(\frac{1}{e^{\mathsf{neg}\left(s\right)} + 1}\right)}^{c\_p}}{{\left(\frac{1}{\color{blue}{e^{\mathsf{neg}\left(t\right)}} + 1}\right)}^{c\_p}} \]
                13. lower-neg.f6491.4

                  \[\leadsto \frac{{\left(\frac{1}{e^{-s} + 1}\right)}^{c\_p}}{{\left(\frac{1}{e^{\color{blue}{-t}} + 1}\right)}^{c\_p}} \]
              5. Applied rewrites91.4%

                \[\leadsto \color{blue}{\frac{{\left(\frac{1}{e^{-s} + 1}\right)}^{c\_p}}{{\left(\frac{1}{e^{-t} + 1}\right)}^{c\_p}}} \]
              6. Taylor expanded in c_p around 0

                \[\leadsto 1 \]
              7. Step-by-step derivation
                1. Applied rewrites91.4%

                  \[\leadsto 1 \]
                2. Add Preprocessing

                Developer Target 1: 96.3% accurate, 1.4× speedup?

                \[\begin{array}{l} \\ {\left(\frac{1 + e^{-t}}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(\frac{1 + e^{t}}{1 + e^{s}}\right)}^{c\_n} \end{array} \]
                (FPCore (c_p c_n t s)
                 :precision binary64
                 (*
                  (pow (/ (+ 1.0 (exp (- t))) (+ 1.0 (exp (- s)))) c_p)
                  (pow (/ (+ 1.0 (exp t)) (+ 1.0 (exp s))) c_n)))
                double code(double c_p, double c_n, double t, double s) {
                	return pow(((1.0 + exp(-t)) / (1.0 + exp(-s))), c_p) * pow(((1.0 + exp(t)) / (1.0 + exp(s))), c_n);
                }
                
                real(8) function code(c_p, c_n, t, s)
                    real(8), intent (in) :: c_p
                    real(8), intent (in) :: c_n
                    real(8), intent (in) :: t
                    real(8), intent (in) :: s
                    code = (((1.0d0 + exp(-t)) / (1.0d0 + exp(-s))) ** c_p) * (((1.0d0 + exp(t)) / (1.0d0 + exp(s))) ** c_n)
                end function
                
                public static double code(double c_p, double c_n, double t, double s) {
                	return Math.pow(((1.0 + Math.exp(-t)) / (1.0 + Math.exp(-s))), c_p) * Math.pow(((1.0 + Math.exp(t)) / (1.0 + Math.exp(s))), c_n);
                }
                
                def code(c_p, c_n, t, s):
                	return math.pow(((1.0 + math.exp(-t)) / (1.0 + math.exp(-s))), c_p) * math.pow(((1.0 + math.exp(t)) / (1.0 + math.exp(s))), c_n)
                
                function code(c_p, c_n, t, s)
                	return Float64((Float64(Float64(1.0 + exp(Float64(-t))) / Float64(1.0 + exp(Float64(-s)))) ^ c_p) * (Float64(Float64(1.0 + exp(t)) / Float64(1.0 + exp(s))) ^ c_n))
                end
                
                function tmp = code(c_p, c_n, t, s)
                	tmp = (((1.0 + exp(-t)) / (1.0 + exp(-s))) ^ c_p) * (((1.0 + exp(t)) / (1.0 + exp(s))) ^ c_n);
                end
                
                code[c$95$p_, c$95$n_, t_, s_] := N[(N[Power[N[(N[(1.0 + N[Exp[(-t)], $MachinePrecision]), $MachinePrecision] / N[(1.0 + N[Exp[(-s)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], c$95$p], $MachinePrecision] * N[Power[N[(N[(1.0 + N[Exp[t], $MachinePrecision]), $MachinePrecision] / N[(1.0 + N[Exp[s], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], c$95$n], $MachinePrecision]), $MachinePrecision]
                
                \begin{array}{l}
                
                \\
                {\left(\frac{1 + e^{-t}}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(\frac{1 + e^{t}}{1 + e^{s}}\right)}^{c\_n}
                \end{array}
                

                Reproduce

                ?
                herbie shell --seed 2024235 
                (FPCore (c_p c_n t s)
                  :name "Harley's example"
                  :precision binary64
                  :pre (and (< 0.0 c_p) (< 0.0 c_n))
                
                  :alt
                  (! :herbie-platform default (* (pow (/ (+ 1 (exp (- t))) (+ 1 (exp (- s)))) c_p) (pow (/ (+ 1 (exp t)) (+ 1 (exp s))) c_n)))
                
                  (/ (* (pow (/ 1.0 (+ 1.0 (exp (- s)))) c_p) (pow (- 1.0 (/ 1.0 (+ 1.0 (exp (- s))))) c_n)) (* (pow (/ 1.0 (+ 1.0 (exp (- t)))) c_p) (pow (- 1.0 (/ 1.0 (+ 1.0 (exp (- t))))) c_n))))