Hyperbolic secant

Percentage Accurate: 100.0% → 100.0%
Time: 4.5s
Alternatives: 8
Speedup: 1.9×

Specification

?
\[\begin{array}{l} \\ \frac{2}{e^{x} + e^{-x}} \end{array} \]
(FPCore (x) :precision binary64 (/ 2.0 (+ (exp x) (exp (- x)))))
double code(double x) {
	return 2.0 / (exp(x) + exp(-x));
}
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 = 2.0d0 / (exp(x) + exp(-x))
end function
public static double code(double x) {
	return 2.0 / (Math.exp(x) + Math.exp(-x));
}
def code(x):
	return 2.0 / (math.exp(x) + math.exp(-x))
function code(x)
	return Float64(2.0 / Float64(exp(x) + exp(Float64(-x))))
end
function tmp = code(x)
	tmp = 2.0 / (exp(x) + exp(-x));
end
code[x_] := N[(2.0 / N[(N[Exp[x], $MachinePrecision] + N[Exp[(-x)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{2}{e^{x} + e^{-x}}
\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 8 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: 100.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{2}{e^{x} + e^{-x}} \end{array} \]
(FPCore (x) :precision binary64 (/ 2.0 (+ (exp x) (exp (- x)))))
double code(double x) {
	return 2.0 / (exp(x) + exp(-x));
}
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 = 2.0d0 / (exp(x) + exp(-x))
end function
public static double code(double x) {
	return 2.0 / (Math.exp(x) + Math.exp(-x));
}
def code(x):
	return 2.0 / (math.exp(x) + math.exp(-x))
function code(x)
	return Float64(2.0 / Float64(exp(x) + exp(Float64(-x))))
end
function tmp = code(x)
	tmp = 2.0 / (exp(x) + exp(-x));
end
code[x_] := N[(2.0 / N[(N[Exp[x], $MachinePrecision] + N[Exp[(-x)], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{2}{e^{x} + e^{-x}}
\end{array}

Alternative 1: 100.0% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \frac{1}{\cosh x} \end{array} \]
(FPCore (x) :precision binary64 (/ 1.0 (cosh x)))
double code(double x) {
	return 1.0 / cosh(x);
}
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 = 1.0d0 / cosh(x)
end function
public static double code(double x) {
	return 1.0 / Math.cosh(x);
}
def code(x):
	return 1.0 / math.cosh(x)
function code(x)
	return Float64(1.0 / cosh(x))
end
function tmp = code(x)
	tmp = 1.0 / cosh(x);
end
code[x_] := N[(1.0 / N[Cosh[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{\cosh x}
\end{array}
Derivation
  1. Initial program 100.0%

    \[\frac{2}{e^{x} + e^{-x}} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{2}{e^{x} + e^{-x}}} \]
    2. lift-+.f64N/A

      \[\leadsto \frac{2}{\color{blue}{e^{x} + e^{-x}}} \]
    3. lift-exp.f64N/A

      \[\leadsto \frac{2}{\color{blue}{e^{x}} + e^{-x}} \]
    4. lift-exp.f64N/A

      \[\leadsto \frac{2}{e^{x} + \color{blue}{e^{-x}}} \]
    5. lift-neg.f64N/A

      \[\leadsto \frac{2}{e^{x} + e^{\color{blue}{\mathsf{neg}\left(x\right)}}} \]
    6. cosh-undefN/A

      \[\leadsto \frac{2}{\color{blue}{2 \cdot \cosh x}} \]
    7. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{2}{2}}{\cosh x}} \]
    8. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{1}}{\cosh x} \]
    9. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
    10. lower-cosh.f64100.0

      \[\leadsto \frac{1}{\color{blue}{\cosh x}} \]
  4. Applied rewrites100.0%

    \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
  5. Add Preprocessing

Alternative 2: 92.3% accurate, 4.8× speedup?

\[\begin{array}{l} \\ \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right) \cdot x, x, 1\right)} \end{array} \]
(FPCore (x)
 :precision binary64
 (/
  1.0
  (fma
   (*
    (fma (fma 0.001388888888888889 (* x x) 0.041666666666666664) (* x x) 0.5)
    x)
   x
   1.0)))
double code(double x) {
	return 1.0 / fma((fma(fma(0.001388888888888889, (x * x), 0.041666666666666664), (x * x), 0.5) * x), x, 1.0);
}
function code(x)
	return Float64(1.0 / fma(Float64(fma(fma(0.001388888888888889, Float64(x * x), 0.041666666666666664), Float64(x * x), 0.5) * x), x, 1.0))
end
code[x_] := N[(1.0 / N[(N[(N[(N[(0.001388888888888889 * N[(x * x), $MachinePrecision] + 0.041666666666666664), $MachinePrecision] * N[(x * x), $MachinePrecision] + 0.5), $MachinePrecision] * x), $MachinePrecision] * x + 1.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right) \cdot x, x, 1\right)}
\end{array}
Derivation
  1. Initial program 100.0%

    \[\frac{2}{e^{x} + e^{-x}} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-/.f64N/A

      \[\leadsto \color{blue}{\frac{2}{e^{x} + e^{-x}}} \]
    2. lift-+.f64N/A

      \[\leadsto \frac{2}{\color{blue}{e^{x} + e^{-x}}} \]
    3. lift-exp.f64N/A

      \[\leadsto \frac{2}{\color{blue}{e^{x}} + e^{-x}} \]
    4. lift-exp.f64N/A

      \[\leadsto \frac{2}{e^{x} + \color{blue}{e^{-x}}} \]
    5. lift-neg.f64N/A

      \[\leadsto \frac{2}{e^{x} + e^{\color{blue}{\mathsf{neg}\left(x\right)}}} \]
    6. cosh-undefN/A

      \[\leadsto \frac{2}{\color{blue}{2 \cdot \cosh x}} \]
    7. associate-/r*N/A

      \[\leadsto \color{blue}{\frac{\frac{2}{2}}{\cosh x}} \]
    8. metadata-evalN/A

      \[\leadsto \frac{\color{blue}{1}}{\cosh x} \]
    9. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
    10. lower-cosh.f64100.0

      \[\leadsto \frac{1}{\color{blue}{\cosh x}} \]
  4. Applied rewrites100.0%

    \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
  5. Taylor expanded in x around 0

    \[\leadsto \frac{1}{\color{blue}{1 + {x}^{2} \cdot \left(\frac{1}{2} + {x}^{2} \cdot \left(\frac{1}{24} + \frac{1}{720} \cdot {x}^{2}\right)\right)}} \]
  6. Step-by-step derivation
    1. Applied rewrites92.7%

      \[\leadsto \frac{1}{\color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right), x \cdot x, 1\right)}} \]
    2. Step-by-step derivation
      1. Applied rewrites92.7%

        \[\leadsto \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right) \cdot x, \color{blue}{x}, 1\right)} \]
      2. Add Preprocessing

      Alternative 3: 92.1% accurate, 4.9× speedup?

      \[\begin{array}{l} \\ \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889 \cdot \left(x \cdot x\right), x \cdot x, 0.5\right) \cdot x, x, 1\right)} \end{array} \]
      (FPCore (x)
       :precision binary64
       (/ 1.0 (fma (* (fma (* 0.001388888888888889 (* x x)) (* x x) 0.5) x) x 1.0)))
      double code(double x) {
      	return 1.0 / fma((fma((0.001388888888888889 * (x * x)), (x * x), 0.5) * x), x, 1.0);
      }
      
      function code(x)
      	return Float64(1.0 / fma(Float64(fma(Float64(0.001388888888888889 * Float64(x * x)), Float64(x * x), 0.5) * x), x, 1.0))
      end
      
      code[x_] := N[(1.0 / N[(N[(N[(N[(0.001388888888888889 * N[(x * x), $MachinePrecision]), $MachinePrecision] * N[(x * x), $MachinePrecision] + 0.5), $MachinePrecision] * x), $MachinePrecision] * x + 1.0), $MachinePrecision]), $MachinePrecision]
      
      \begin{array}{l}
      
      \\
      \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889 \cdot \left(x \cdot x\right), x \cdot x, 0.5\right) \cdot x, x, 1\right)}
      \end{array}
      
      Derivation
      1. Initial program 100.0%

        \[\frac{2}{e^{x} + e^{-x}} \]
      2. Add Preprocessing
      3. Step-by-step derivation
        1. lift-/.f64N/A

          \[\leadsto \color{blue}{\frac{2}{e^{x} + e^{-x}}} \]
        2. lift-+.f64N/A

          \[\leadsto \frac{2}{\color{blue}{e^{x} + e^{-x}}} \]
        3. lift-exp.f64N/A

          \[\leadsto \frac{2}{\color{blue}{e^{x}} + e^{-x}} \]
        4. lift-exp.f64N/A

          \[\leadsto \frac{2}{e^{x} + \color{blue}{e^{-x}}} \]
        5. lift-neg.f64N/A

          \[\leadsto \frac{2}{e^{x} + e^{\color{blue}{\mathsf{neg}\left(x\right)}}} \]
        6. cosh-undefN/A

          \[\leadsto \frac{2}{\color{blue}{2 \cdot \cosh x}} \]
        7. associate-/r*N/A

          \[\leadsto \color{blue}{\frac{\frac{2}{2}}{\cosh x}} \]
        8. metadata-evalN/A

          \[\leadsto \frac{\color{blue}{1}}{\cosh x} \]
        9. lower-/.f64N/A

          \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
        10. lower-cosh.f64100.0

          \[\leadsto \frac{1}{\color{blue}{\cosh x}} \]
      4. Applied rewrites100.0%

        \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
      5. Taylor expanded in x around 0

        \[\leadsto \frac{1}{\color{blue}{1 + {x}^{2} \cdot \left(\frac{1}{2} + {x}^{2} \cdot \left(\frac{1}{24} + \frac{1}{720} \cdot {x}^{2}\right)\right)}} \]
      6. Step-by-step derivation
        1. Applied rewrites92.7%

          \[\leadsto \frac{1}{\color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right), x \cdot x, 1\right)}} \]
        2. Step-by-step derivation
          1. Applied rewrites92.7%

            \[\leadsto \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889, x \cdot x, 0.041666666666666664\right), x \cdot x, 0.5\right) \cdot x, \color{blue}{x}, 1\right)} \]
          2. Taylor expanded in x around inf

            \[\leadsto \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(\frac{1}{720} \cdot {x}^{2}, x \cdot x, \frac{1}{2}\right) \cdot x, x, 1\right)} \]
          3. Step-by-step derivation
            1. Applied rewrites92.6%

              \[\leadsto \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.001388888888888889 \cdot \left(x \cdot x\right), x \cdot x, 0.5\right) \cdot x, x, 1\right)} \]
            2. Add Preprocessing

            Alternative 4: 88.2% accurate, 6.4× speedup?

            \[\begin{array}{l} \\ \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x \cdot x, 0.5\right) \cdot x, x, 1\right)} \end{array} \]
            (FPCore (x)
             :precision binary64
             (/ 1.0 (fma (* (fma 0.041666666666666664 (* x x) 0.5) x) x 1.0)))
            double code(double x) {
            	return 1.0 / fma((fma(0.041666666666666664, (x * x), 0.5) * x), x, 1.0);
            }
            
            function code(x)
            	return Float64(1.0 / fma(Float64(fma(0.041666666666666664, Float64(x * x), 0.5) * x), x, 1.0))
            end
            
            code[x_] := N[(1.0 / N[(N[(N[(0.041666666666666664 * N[(x * x), $MachinePrecision] + 0.5), $MachinePrecision] * x), $MachinePrecision] * x + 1.0), $MachinePrecision]), $MachinePrecision]
            
            \begin{array}{l}
            
            \\
            \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x \cdot x, 0.5\right) \cdot x, x, 1\right)}
            \end{array}
            
            Derivation
            1. Initial program 100.0%

              \[\frac{2}{e^{x} + e^{-x}} \]
            2. Add Preprocessing
            3. Step-by-step derivation
              1. lift-/.f64N/A

                \[\leadsto \color{blue}{\frac{2}{e^{x} + e^{-x}}} \]
              2. lift-+.f64N/A

                \[\leadsto \frac{2}{\color{blue}{e^{x} + e^{-x}}} \]
              3. lift-exp.f64N/A

                \[\leadsto \frac{2}{\color{blue}{e^{x}} + e^{-x}} \]
              4. lift-exp.f64N/A

                \[\leadsto \frac{2}{e^{x} + \color{blue}{e^{-x}}} \]
              5. lift-neg.f64N/A

                \[\leadsto \frac{2}{e^{x} + e^{\color{blue}{\mathsf{neg}\left(x\right)}}} \]
              6. cosh-undefN/A

                \[\leadsto \frac{2}{\color{blue}{2 \cdot \cosh x}} \]
              7. associate-/r*N/A

                \[\leadsto \color{blue}{\frac{\frac{2}{2}}{\cosh x}} \]
              8. metadata-evalN/A

                \[\leadsto \frac{\color{blue}{1}}{\cosh x} \]
              9. lower-/.f64N/A

                \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
              10. lower-cosh.f64100.0

                \[\leadsto \frac{1}{\color{blue}{\cosh x}} \]
            4. Applied rewrites100.0%

              \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
            5. Taylor expanded in x around 0

              \[\leadsto \frac{1}{\color{blue}{1 + {x}^{2} \cdot \left(\frac{1}{2} + \frac{1}{24} \cdot {x}^{2}\right)}} \]
            6. Step-by-step derivation
              1. Applied rewrites88.2%

                \[\leadsto \frac{1}{\color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x \cdot x, 0.5\right), x \cdot x, 1\right)}} \]
              2. Step-by-step derivation
                1. Applied rewrites88.2%

                  \[\leadsto \frac{1}{\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x \cdot x, 0.5\right) \cdot x, \color{blue}{x}, 1\right)} \]
                2. Add Preprocessing

                Alternative 5: 87.8% accurate, 6.6× speedup?

                \[\begin{array}{l} \\ \frac{1}{\mathsf{fma}\left(0.041666666666666664 \cdot \left(x \cdot x\right), x \cdot x, 1\right)} \end{array} \]
                (FPCore (x)
                 :precision binary64
                 (/ 1.0 (fma (* 0.041666666666666664 (* x x)) (* x x) 1.0)))
                double code(double x) {
                	return 1.0 / fma((0.041666666666666664 * (x * x)), (x * x), 1.0);
                }
                
                function code(x)
                	return Float64(1.0 / fma(Float64(0.041666666666666664 * Float64(x * x)), Float64(x * x), 1.0))
                end
                
                code[x_] := N[(1.0 / N[(N[(0.041666666666666664 * N[(x * x), $MachinePrecision]), $MachinePrecision] * N[(x * x), $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision]
                
                \begin{array}{l}
                
                \\
                \frac{1}{\mathsf{fma}\left(0.041666666666666664 \cdot \left(x \cdot x\right), x \cdot x, 1\right)}
                \end{array}
                
                Derivation
                1. Initial program 100.0%

                  \[\frac{2}{e^{x} + e^{-x}} \]
                2. Add Preprocessing
                3. Step-by-step derivation
                  1. lift-/.f64N/A

                    \[\leadsto \color{blue}{\frac{2}{e^{x} + e^{-x}}} \]
                  2. lift-+.f64N/A

                    \[\leadsto \frac{2}{\color{blue}{e^{x} + e^{-x}}} \]
                  3. lift-exp.f64N/A

                    \[\leadsto \frac{2}{\color{blue}{e^{x}} + e^{-x}} \]
                  4. lift-exp.f64N/A

                    \[\leadsto \frac{2}{e^{x} + \color{blue}{e^{-x}}} \]
                  5. lift-neg.f64N/A

                    \[\leadsto \frac{2}{e^{x} + e^{\color{blue}{\mathsf{neg}\left(x\right)}}} \]
                  6. cosh-undefN/A

                    \[\leadsto \frac{2}{\color{blue}{2 \cdot \cosh x}} \]
                  7. associate-/r*N/A

                    \[\leadsto \color{blue}{\frac{\frac{2}{2}}{\cosh x}} \]
                  8. metadata-evalN/A

                    \[\leadsto \frac{\color{blue}{1}}{\cosh x} \]
                  9. lower-/.f64N/A

                    \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
                  10. lower-cosh.f64100.0

                    \[\leadsto \frac{1}{\color{blue}{\cosh x}} \]
                4. Applied rewrites100.0%

                  \[\leadsto \color{blue}{\frac{1}{\cosh x}} \]
                5. Taylor expanded in x around 0

                  \[\leadsto \frac{1}{\color{blue}{1 + {x}^{2} \cdot \left(\frac{1}{2} + \frac{1}{24} \cdot {x}^{2}\right)}} \]
                6. Step-by-step derivation
                  1. Applied rewrites88.2%

                    \[\leadsto \frac{1}{\color{blue}{\mathsf{fma}\left(\mathsf{fma}\left(0.041666666666666664, x \cdot x, 0.5\right), x \cdot x, 1\right)}} \]
                  2. Taylor expanded in x around inf

                    \[\leadsto \frac{1}{\mathsf{fma}\left(\frac{1}{24} \cdot {x}^{2}, \color{blue}{x} \cdot x, 1\right)} \]
                  3. Step-by-step derivation
                    1. Applied rewrites87.6%

                      \[\leadsto \frac{1}{\mathsf{fma}\left(0.041666666666666664 \cdot \left(x \cdot x\right), \color{blue}{x} \cdot x, 1\right)} \]
                    2. Add Preprocessing

                    Alternative 6: 62.7% accurate, 9.4× speedup?

                    \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 1.2:\\ \;\;\;\;\mathsf{fma}\left(-0.5, x \cdot x, 1\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{2}{x \cdot x}\\ \end{array} \end{array} \]
                    (FPCore (x)
                     :precision binary64
                     (if (<= x 1.2) (fma -0.5 (* x x) 1.0) (/ 2.0 (* x x))))
                    double code(double x) {
                    	double tmp;
                    	if (x <= 1.2) {
                    		tmp = fma(-0.5, (x * x), 1.0);
                    	} else {
                    		tmp = 2.0 / (x * x);
                    	}
                    	return tmp;
                    }
                    
                    function code(x)
                    	tmp = 0.0
                    	if (x <= 1.2)
                    		tmp = fma(-0.5, Float64(x * x), 1.0);
                    	else
                    		tmp = Float64(2.0 / Float64(x * x));
                    	end
                    	return tmp
                    end
                    
                    code[x_] := If[LessEqual[x, 1.2], N[(-0.5 * N[(x * x), $MachinePrecision] + 1.0), $MachinePrecision], N[(2.0 / N[(x * x), $MachinePrecision]), $MachinePrecision]]
                    
                    \begin{array}{l}
                    
                    \\
                    \begin{array}{l}
                    \mathbf{if}\;x \leq 1.2:\\
                    \;\;\;\;\mathsf{fma}\left(-0.5, x \cdot x, 1\right)\\
                    
                    \mathbf{else}:\\
                    \;\;\;\;\frac{2}{x \cdot x}\\
                    
                    
                    \end{array}
                    \end{array}
                    
                    Derivation
                    1. Split input into 2 regimes
                    2. if x < 1.19999999999999996

                      1. Initial program 100.0%

                        \[\frac{2}{e^{x} + e^{-x}} \]
                      2. Add Preprocessing
                      3. Taylor expanded in x around 0

                        \[\leadsto \color{blue}{1 + \frac{-1}{2} \cdot {x}^{2}} \]
                      4. Step-by-step derivation
                        1. Applied rewrites68.4%

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

                        if 1.19999999999999996 < x

                        1. Initial program 100.0%

                          \[\frac{2}{e^{x} + e^{-x}} \]
                        2. Add Preprocessing
                        3. Taylor expanded in x around 0

                          \[\leadsto \frac{2}{\color{blue}{2 + {x}^{2}}} \]
                        4. Step-by-step derivation
                          1. Applied rewrites52.9%

                            \[\leadsto \frac{2}{\color{blue}{\mathsf{fma}\left(x, x, 2\right)}} \]
                          2. Taylor expanded in x around inf

                            \[\leadsto \frac{2}{{x}^{\color{blue}{2}}} \]
                          3. Step-by-step derivation
                            1. Applied rewrites52.9%

                              \[\leadsto \frac{2}{x \cdot \color{blue}{x}} \]
                          4. Recombined 2 regimes into one program.
                          5. Add Preprocessing

                          Alternative 7: 75.8% accurate, 12.1× speedup?

                          \[\begin{array}{l} \\ \frac{2}{\mathsf{fma}\left(x, x, 2\right)} \end{array} \]
                          (FPCore (x) :precision binary64 (/ 2.0 (fma x x 2.0)))
                          double code(double x) {
                          	return 2.0 / fma(x, x, 2.0);
                          }
                          
                          function code(x)
                          	return Float64(2.0 / fma(x, x, 2.0))
                          end
                          
                          code[x_] := N[(2.0 / N[(x * x + 2.0), $MachinePrecision]), $MachinePrecision]
                          
                          \begin{array}{l}
                          
                          \\
                          \frac{2}{\mathsf{fma}\left(x, x, 2\right)}
                          \end{array}
                          
                          Derivation
                          1. Initial program 100.0%

                            \[\frac{2}{e^{x} + e^{-x}} \]
                          2. Add Preprocessing
                          3. Taylor expanded in x around 0

                            \[\leadsto \frac{2}{\color{blue}{2 + {x}^{2}}} \]
                          4. Step-by-step derivation
                            1. Applied rewrites75.7%

                              \[\leadsto \frac{2}{\color{blue}{\mathsf{fma}\left(x, x, 2\right)}} \]
                            2. Add Preprocessing

                            Alternative 8: 50.8% accurate, 217.0× speedup?

                            \[\begin{array}{l} \\ 1 \end{array} \]
                            (FPCore (x) :precision binary64 1.0)
                            double code(double x) {
                            	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(x)
                            use fmin_fmax_functions
                                real(8), intent (in) :: x
                                code = 1.0d0
                            end function
                            
                            public static double code(double x) {
                            	return 1.0;
                            }
                            
                            def code(x):
                            	return 1.0
                            
                            function code(x)
                            	return 1.0
                            end
                            
                            function tmp = code(x)
                            	tmp = 1.0;
                            end
                            
                            code[x_] := 1.0
                            
                            \begin{array}{l}
                            
                            \\
                            1
                            \end{array}
                            
                            Derivation
                            1. Initial program 100.0%

                              \[\frac{2}{e^{x} + e^{-x}} \]
                            2. Add Preprocessing
                            3. Taylor expanded in x around 0

                              \[\leadsto \color{blue}{1} \]
                            4. Step-by-step derivation
                              1. Applied rewrites51.4%

                                \[\leadsto \color{blue}{1} \]
                              2. Add Preprocessing

                              Reproduce

                              ?
                              herbie shell --seed 2025026 
                              (FPCore (x)
                                :name "Hyperbolic secant"
                                :precision binary64
                                (/ 2.0 (+ (exp x) (exp (- x)))))