Harley's example

Percentage Accurate: 90.4% → 98.1%
Time: 1.2min
Alternatives: 4
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));
}
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(c_p, c_n, t, s)
use fmin_fmax_functions
    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 4 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: 90.4% 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));
}
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(c_p, c_n, t, s)
use fmin_fmax_functions
    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: 98.1% accurate, 6.3× speedup?

\[\begin{array}{l} \\ e^{c\_n \cdot \left(\left(\left(\mathsf{fma}\left(-0.00034722222222222224, s \cdot s, 0.005208333333333333\right) \cdot \left(s \cdot s\right) - 0.125\right) \cdot s - 0.5\right) \cdot s\right)} \end{array} \]
(FPCore (c_p c_n t s)
 :precision binary64
 (exp
  (*
   c_n
   (*
    (-
     (*
      (-
       (* (fma -0.00034722222222222224 (* s s) 0.005208333333333333) (* s s))
       0.125)
      s)
     0.5)
    s))))
double code(double c_p, double c_n, double t, double s) {
	return exp((c_n * (((((fma(-0.00034722222222222224, (s * s), 0.005208333333333333) * (s * s)) - 0.125) * s) - 0.5) * s)));
}
function code(c_p, c_n, t, s)
	return exp(Float64(c_n * Float64(Float64(Float64(Float64(Float64(fma(-0.00034722222222222224, Float64(s * s), 0.005208333333333333) * Float64(s * s)) - 0.125) * s) - 0.5) * s)))
end
code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(c$95$n * N[(N[(N[(N[(N[(N[(-0.00034722222222222224 * N[(s * s), $MachinePrecision] + 0.005208333333333333), $MachinePrecision] * N[(s * s), $MachinePrecision]), $MachinePrecision] - 0.125), $MachinePrecision] * s), $MachinePrecision] - 0.5), $MachinePrecision] * s), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
e^{c\_n \cdot \left(\left(\left(\mathsf{fma}\left(-0.00034722222222222224, s \cdot s, 0.005208333333333333\right) \cdot \left(s \cdot s\right) - 0.125\right) \cdot s - 0.5\right) \cdot s\right)}
\end{array}
Derivation
  1. Initial program 92.2%

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

    \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n}}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_n}}} \]
  4. Step-by-step derivation
    1. Applied rewrites95.7%

      \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{e^{-s} + 1}\right)}^{c\_n}}{{\left(1 - \frac{1}{e^{-t} + 1}\right)}^{c\_n}}} \]
    2. Applied rewrites98.0%

      \[\leadsto e^{\log \left(1 - {\left(e^{-s} - -1\right)}^{-1}\right) \cdot c\_n - \log \left(1 - {\left(e^{-t} - -1\right)}^{-1}\right) \cdot c\_n} \]
    3. Taylor expanded in t around 0

      \[\leadsto e^{c\_n \cdot \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right) - c\_n \cdot \log \frac{1}{2}} \]
    4. Step-by-step derivation
      1. Applied rewrites97.6%

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

        \[\leadsto e^{c\_n \cdot \left(s \cdot \left(s \cdot \left({s}^{2} \cdot \left(\frac{1}{192} + \frac{-1}{2880} \cdot {s}^{2}\right) - \frac{1}{8}\right) - \frac{1}{2}\right)\right)} \]
      3. Step-by-step derivation
        1. Applied rewrites98.4%

          \[\leadsto e^{c\_n \cdot \left(\left(\left(\mathsf{fma}\left(-0.00034722222222222224, s \cdot s, 0.005208333333333333\right) \cdot \left(s \cdot s\right) - 0.125\right) \cdot s - 0.5\right) \cdot s\right)} \]
        2. Add Preprocessing

        Alternative 2: 97.8% accurate, 7.5× speedup?

        \[\begin{array}{l} \\ e^{c\_n \cdot \left(\left(-0.125 \cdot s - 0.5\right) \cdot s\right)} \end{array} \]
        (FPCore (c_p c_n t s)
         :precision binary64
         (exp (* c_n (* (- (* -0.125 s) 0.5) s))))
        double code(double c_p, double c_n, double t, double s) {
        	return exp((c_n * (((-0.125 * s) - 0.5) * s)));
        }
        
        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(c_p, c_n, t, s)
        use fmin_fmax_functions
            real(8), intent (in) :: c_p
            real(8), intent (in) :: c_n
            real(8), intent (in) :: t
            real(8), intent (in) :: s
            code = exp((c_n * ((((-0.125d0) * s) - 0.5d0) * s)))
        end function
        
        public static double code(double c_p, double c_n, double t, double s) {
        	return Math.exp((c_n * (((-0.125 * s) - 0.5) * s)));
        }
        
        def code(c_p, c_n, t, s):
        	return math.exp((c_n * (((-0.125 * s) - 0.5) * s)))
        
        function code(c_p, c_n, t, s)
        	return exp(Float64(c_n * Float64(Float64(Float64(-0.125 * s) - 0.5) * s)))
        end
        
        function tmp = code(c_p, c_n, t, s)
        	tmp = exp((c_n * (((-0.125 * s) - 0.5) * s)));
        end
        
        code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(c$95$n * N[(N[(N[(-0.125 * s), $MachinePrecision] - 0.5), $MachinePrecision] * s), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
        
        \begin{array}{l}
        
        \\
        e^{c\_n \cdot \left(\left(-0.125 \cdot s - 0.5\right) \cdot s\right)}
        \end{array}
        
        Derivation
        1. Initial program 92.2%

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

          \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n}}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_n}}} \]
        4. Step-by-step derivation
          1. Applied rewrites95.7%

            \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{e^{-s} + 1}\right)}^{c\_n}}{{\left(1 - \frac{1}{e^{-t} + 1}\right)}^{c\_n}}} \]
          2. Applied rewrites98.0%

            \[\leadsto e^{\log \left(1 - {\left(e^{-s} - -1\right)}^{-1}\right) \cdot c\_n - \log \left(1 - {\left(e^{-t} - -1\right)}^{-1}\right) \cdot c\_n} \]
          3. Taylor expanded in t around 0

            \[\leadsto e^{c\_n \cdot \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right) - c\_n \cdot \log \frac{1}{2}} \]
          4. Step-by-step derivation
            1. Applied rewrites97.6%

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

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

                \[\leadsto e^{c\_n \cdot \left(\left(-0.125 \cdot s - 0.5\right) \cdot s\right)} \]
              2. Add Preprocessing

              Alternative 3: 96.1% accurate, 8.1× speedup?

              \[\begin{array}{l} \\ e^{c\_n \cdot \left(-0.5 \cdot s\right)} \end{array} \]
              (FPCore (c_p c_n t s) :precision binary64 (exp (* c_n (* -0.5 s))))
              double code(double c_p, double c_n, double t, double s) {
              	return exp((c_n * (-0.5 * s)));
              }
              
              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(c_p, c_n, t, s)
              use fmin_fmax_functions
                  real(8), intent (in) :: c_p
                  real(8), intent (in) :: c_n
                  real(8), intent (in) :: t
                  real(8), intent (in) :: s
                  code = exp((c_n * ((-0.5d0) * s)))
              end function
              
              public static double code(double c_p, double c_n, double t, double s) {
              	return Math.exp((c_n * (-0.5 * s)));
              }
              
              def code(c_p, c_n, t, s):
              	return math.exp((c_n * (-0.5 * s)))
              
              function code(c_p, c_n, t, s)
              	return exp(Float64(c_n * Float64(-0.5 * s)))
              end
              
              function tmp = code(c_p, c_n, t, s)
              	tmp = exp((c_n * (-0.5 * s)));
              end
              
              code[c$95$p_, c$95$n_, t_, s_] := N[Exp[N[(c$95$n * N[(-0.5 * s), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
              
              \begin{array}{l}
              
              \\
              e^{c\_n \cdot \left(-0.5 \cdot s\right)}
              \end{array}
              
              Derivation
              1. Initial program 92.2%

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

                \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right)}^{c\_n}}{{\left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(t\right)}}\right)}^{c\_n}}} \]
              4. Step-by-step derivation
                1. Applied rewrites95.7%

                  \[\leadsto \color{blue}{\frac{{\left(1 - \frac{1}{e^{-s} + 1}\right)}^{c\_n}}{{\left(1 - \frac{1}{e^{-t} + 1}\right)}^{c\_n}}} \]
                2. Applied rewrites98.0%

                  \[\leadsto e^{\log \left(1 - {\left(e^{-s} - -1\right)}^{-1}\right) \cdot c\_n - \log \left(1 - {\left(e^{-t} - -1\right)}^{-1}\right) \cdot c\_n} \]
                3. Taylor expanded in t around 0

                  \[\leadsto e^{c\_n \cdot \log \left(1 - \frac{1}{1 + e^{\mathsf{neg}\left(s\right)}}\right) - c\_n \cdot \log \frac{1}{2}} \]
                4. Step-by-step derivation
                  1. Applied rewrites97.6%

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

                    \[\leadsto e^{c\_n \cdot \left(\frac{-1}{2} \cdot s\right)} \]
                  3. Step-by-step derivation
                    1. Applied rewrites98.0%

                      \[\leadsto e^{c\_n \cdot \left(-0.5 \cdot s\right)} \]
                    2. Add Preprocessing

                    Alternative 4: 93.9% 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;
                    }
                    
                    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(c_p, c_n, t, s)
                    use fmin_fmax_functions
                        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 92.2%

                      \[\frac{{\left(\frac{1}{1 + e^{-s}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-s}}\right)}^{c\_n}}{{\left(\frac{1}{1 + e^{-t}}\right)}^{c\_p} \cdot {\left(1 - \frac{1}{1 + e^{-t}}\right)}^{c\_n}} \]
                    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. Applied rewrites94.2%

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

                        \[\leadsto 1 \]
                      3. Step-by-step derivation
                        1. Applied rewrites96.5%

                          \[\leadsto 1 \]
                        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);
                        }
                        
                        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(c_p, c_n, t, s)
                        use fmin_fmax_functions
                            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 2025019 
                        (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))))