Hyperbolic secant

Percentage Accurate: 100.0% → 100.0%
Time: 5.7s
Alternatives: 10
Speedup: 1.0×

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));
}
real(8) function code(x)
    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 10 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));
}
real(8) function code(x)
    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, 1.0× 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));
}
real(8) function code(x)
    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}
Derivation
  1. Initial program 100.0%

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

Alternative 2: 74.6% accurate, 1.7× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 1.5:\\ \;\;\;\;1 + {x}^{2} \cdot \left(\left(x \cdot x\right) \cdot \left(0.20833333333333334 + \left(x \cdot x\right) \cdot -0.08472222222222223\right) - 0.5\right)\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= x 1.5)
   (+
    1.0
    (*
     (pow x 2.0)
     (-
      (* (* x x) (+ 0.20833333333333334 (* (* x x) -0.08472222222222223)))
      0.5)))
   0.0))
double code(double x) {
	double tmp;
	if (x <= 1.5) {
		tmp = 1.0 + (pow(x, 2.0) * (((x * x) * (0.20833333333333334 + ((x * x) * -0.08472222222222223))) - 0.5));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 1.5d0) then
        tmp = 1.0d0 + ((x ** 2.0d0) * (((x * x) * (0.20833333333333334d0 + ((x * x) * (-0.08472222222222223d0)))) - 0.5d0))
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 1.5) {
		tmp = 1.0 + (Math.pow(x, 2.0) * (((x * x) * (0.20833333333333334 + ((x * x) * -0.08472222222222223))) - 0.5));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 1.5:
		tmp = 1.0 + (math.pow(x, 2.0) * (((x * x) * (0.20833333333333334 + ((x * x) * -0.08472222222222223))) - 0.5))
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 1.5)
		tmp = Float64(1.0 + Float64((x ^ 2.0) * Float64(Float64(Float64(x * x) * Float64(0.20833333333333334 + Float64(Float64(x * x) * -0.08472222222222223))) - 0.5)));
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 1.5)
		tmp = 1.0 + ((x ^ 2.0) * (((x * x) * (0.20833333333333334 + ((x * x) * -0.08472222222222223))) - 0.5));
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 1.5], N[(1.0 + N[(N[Power[x, 2.0], $MachinePrecision] * N[(N[(N[(x * x), $MachinePrecision] * N[(0.20833333333333334 + N[(N[(x * x), $MachinePrecision] * -0.08472222222222223), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - 0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 1.5:\\
\;\;\;\;1 + {x}^{2} \cdot \left(\left(x \cdot x\right) \cdot \left(0.20833333333333334 + \left(x \cdot x\right) \cdot -0.08472222222222223\right) - 0.5\right)\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 1.5

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 69.7%

      \[\leadsto \color{blue}{1 + {x}^{2} \cdot \left({x}^{2} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot {x}^{2}\right) - 0.5\right)} \]
    4. Step-by-step derivation
      1. unpow269.7%

        \[\leadsto 1 + {x}^{2} \cdot \left({x}^{2} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot \color{blue}{\left(x \cdot x\right)}\right) - 0.5\right) \]
    5. Applied egg-rr69.7%

      \[\leadsto 1 + {x}^{2} \cdot \left({x}^{2} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot \color{blue}{\left(x \cdot x\right)}\right) - 0.5\right) \]
    6. Step-by-step derivation
      1. unpow269.7%

        \[\leadsto 1 + {x}^{2} \cdot \left({x}^{2} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot \color{blue}{\left(x \cdot x\right)}\right) - 0.5\right) \]
    7. Applied egg-rr69.7%

      \[\leadsto 1 + {x}^{2} \cdot \left(\color{blue}{\left(x \cdot x\right)} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot \left(x \cdot x\right)\right) - 0.5\right) \]

    if 1.5 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification76.6%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 1.5:\\ \;\;\;\;1 + {x}^{2} \cdot \left(\left(x \cdot x\right) \cdot \left(0.20833333333333334 + \left(x \cdot x\right) \cdot -0.08472222222222223\right) - 0.5\right)\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \]
  5. Add Preprocessing

Alternative 3: 91.2% accurate, 1.7× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 100:\\ \;\;\;\;\frac{2}{e^{x} + \left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= x 100.0)
   (/
    2.0
    (+
     (exp x)
     (+ 1.0 (* x (+ (* x (+ 0.5 (* x -0.16666666666666666))) -1.0)))))
   0.0))
double code(double x) {
	double tmp;
	if (x <= 100.0) {
		tmp = 2.0 / (exp(x) + (1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 100.0d0) then
        tmp = 2.0d0 / (exp(x) + (1.0d0 + (x * ((x * (0.5d0 + (x * (-0.16666666666666666d0)))) + (-1.0d0)))))
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 100.0) {
		tmp = 2.0 / (Math.exp(x) + (1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 100.0:
		tmp = 2.0 / (math.exp(x) + (1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))))
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 100.0)
		tmp = Float64(2.0 / Float64(exp(x) + Float64(1.0 + Float64(x * Float64(Float64(x * Float64(0.5 + Float64(x * -0.16666666666666666))) + -1.0)))));
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 100.0)
		tmp = 2.0 / (exp(x) + (1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))));
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 100.0], N[(2.0 / N[(N[Exp[x], $MachinePrecision] + N[(1.0 + N[(x * N[(N[(x * N[(0.5 + N[(x * -0.16666666666666666), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 100:\\
\;\;\;\;\frac{2}{e^{x} + \left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right)}\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 100

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 88.8%

      \[\leadsto \frac{2}{e^{x} + \color{blue}{\left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)}} \]

    if 100 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification91.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 100:\\ \;\;\;\;\frac{2}{e^{x} + \left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \]
  5. Add Preprocessing

Alternative 4: 87.1% accurate, 1.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 360:\\ \;\;\;\;\frac{2}{\mathsf{fma}\left(x, x, 2\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x) :precision binary64 (if (<= x 360.0) (/ 2.0 (fma x x 2.0)) 0.0))
double code(double x) {
	double tmp;
	if (x <= 360.0) {
		tmp = 2.0 / fma(x, x, 2.0);
	} else {
		tmp = 0.0;
	}
	return tmp;
}
function code(x)
	tmp = 0.0
	if (x <= 360.0)
		tmp = Float64(2.0 / fma(x, x, 2.0));
	else
		tmp = 0.0;
	end
	return tmp
end
code[x_] := If[LessEqual[x, 360.0], N[(2.0 / N[(x * x + 2.0), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 360:\\
\;\;\;\;\frac{2}{\mathsf{fma}\left(x, x, 2\right)}\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 360

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 83.9%

      \[\leadsto \frac{2}{\color{blue}{2 + {x}^{2}}} \]
    4. Step-by-step derivation
      1. +-commutative83.9%

        \[\leadsto \frac{2}{\color{blue}{{x}^{2} + 2}} \]
      2. unpow283.9%

        \[\leadsto \frac{2}{\color{blue}{x \cdot x} + 2} \]
      3. fma-define83.9%

        \[\leadsto \frac{2}{\color{blue}{\mathsf{fma}\left(x, x, 2\right)}} \]
    5. Simplified83.9%

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

    if 360 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 5: 74.2% accurate, 6.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 360:\\ \;\;\;\;\frac{2}{\left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right) + \left(1 + x \cdot \left(1 + x \cdot \left(0.5 + x \cdot 0.16666666666666666\right)\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= x 360.0)
   (/
    2.0
    (+
     (+ 1.0 (* x (+ (* x (+ 0.5 (* x -0.16666666666666666))) -1.0)))
     (+ 1.0 (* x (+ 1.0 (* x (+ 0.5 (* x 0.16666666666666666))))))))
   0.0))
double code(double x) {
	double tmp;
	if (x <= 360.0) {
		tmp = 2.0 / ((1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))) + (1.0 + (x * (1.0 + (x * (0.5 + (x * 0.16666666666666666)))))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 360.0d0) then
        tmp = 2.0d0 / ((1.0d0 + (x * ((x * (0.5d0 + (x * (-0.16666666666666666d0)))) + (-1.0d0)))) + (1.0d0 + (x * (1.0d0 + (x * (0.5d0 + (x * 0.16666666666666666d0)))))))
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 360.0) {
		tmp = 2.0 / ((1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))) + (1.0 + (x * (1.0 + (x * (0.5 + (x * 0.16666666666666666)))))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 360.0:
		tmp = 2.0 / ((1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))) + (1.0 + (x * (1.0 + (x * (0.5 + (x * 0.16666666666666666)))))))
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 360.0)
		tmp = Float64(2.0 / Float64(Float64(1.0 + Float64(x * Float64(Float64(x * Float64(0.5 + Float64(x * -0.16666666666666666))) + -1.0))) + Float64(1.0 + Float64(x * Float64(1.0 + Float64(x * Float64(0.5 + Float64(x * 0.16666666666666666))))))));
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 360.0)
		tmp = 2.0 / ((1.0 + (x * ((x * (0.5 + (x * -0.16666666666666666))) + -1.0))) + (1.0 + (x * (1.0 + (x * (0.5 + (x * 0.16666666666666666)))))));
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 360.0], N[(2.0 / N[(N[(1.0 + N[(x * N[(N[(x * N[(0.5 + N[(x * -0.16666666666666666), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(1.0 + N[(x * N[(1.0 + N[(x * N[(0.5 + N[(x * 0.16666666666666666), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 360:\\
\;\;\;\;\frac{2}{\left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right) + \left(1 + x \cdot \left(1 + x \cdot \left(0.5 + x \cdot 0.16666666666666666\right)\right)\right)}\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 360

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 88.8%

      \[\leadsto \frac{2}{e^{x} + \color{blue}{\left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)}} \]
    4. Taylor expanded in x around 0 68.6%

      \[\leadsto \frac{2}{\color{blue}{\left(1 + x \cdot \left(1 + x \cdot \left(0.5 + 0.16666666666666666 \cdot x\right)\right)\right)} + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
    5. Step-by-step derivation
      1. *-lft-identity68.6%

        \[\leadsto \frac{2}{\left(1 + x \cdot \color{blue}{\left(1 \cdot \left(1 + x \cdot \left(0.5 + 0.16666666666666666 \cdot x\right)\right)\right)}\right) + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
      2. *-lft-identity68.6%

        \[\leadsto \frac{2}{\left(1 + x \cdot \color{blue}{\left(1 + x \cdot \left(0.5 + 0.16666666666666666 \cdot x\right)\right)}\right) + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
      3. *-commutative68.6%

        \[\leadsto \frac{2}{\left(1 + x \cdot \left(1 + x \cdot \left(0.5 + \color{blue}{x \cdot 0.16666666666666666}\right)\right)\right) + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
    6. Simplified68.6%

      \[\leadsto \frac{2}{\color{blue}{\left(1 + x \cdot \left(1 + x \cdot \left(0.5 + x \cdot 0.16666666666666666\right)\right)\right)} + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]

    if 360 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification75.7%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 360:\\ \;\;\;\;\frac{2}{\left(1 + x \cdot \left(x \cdot \left(0.5 + x \cdot -0.16666666666666666\right) + -1\right)\right) + \left(1 + x \cdot \left(1 + x \cdot \left(0.5 + x \cdot 0.16666666666666666\right)\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \]
  5. Add Preprocessing

Alternative 6: 87.1% accurate, 7.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 360:\\ \;\;\;\;\frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(x \cdot 0.5 + -1\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= x 360.0)
   (/ 2.0 (+ (+ 1.0 (* x (+ 1.0 (* x 0.5)))) (+ 1.0 (* x (+ (* x 0.5) -1.0)))))
   0.0))
double code(double x) {
	double tmp;
	if (x <= 360.0) {
		tmp = 2.0 / ((1.0 + (x * (1.0 + (x * 0.5)))) + (1.0 + (x * ((x * 0.5) + -1.0))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 360.0d0) then
        tmp = 2.0d0 / ((1.0d0 + (x * (1.0d0 + (x * 0.5d0)))) + (1.0d0 + (x * ((x * 0.5d0) + (-1.0d0)))))
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 360.0) {
		tmp = 2.0 / ((1.0 + (x * (1.0 + (x * 0.5)))) + (1.0 + (x * ((x * 0.5) + -1.0))));
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 360.0:
		tmp = 2.0 / ((1.0 + (x * (1.0 + (x * 0.5)))) + (1.0 + (x * ((x * 0.5) + -1.0))))
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 360.0)
		tmp = Float64(2.0 / Float64(Float64(1.0 + Float64(x * Float64(1.0 + Float64(x * 0.5)))) + Float64(1.0 + Float64(x * Float64(Float64(x * 0.5) + -1.0)))));
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 360.0)
		tmp = 2.0 / ((1.0 + (x * (1.0 + (x * 0.5)))) + (1.0 + (x * ((x * 0.5) + -1.0))));
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 360.0], N[(2.0 / N[(N[(1.0 + N[(x * N[(1.0 + N[(x * 0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(1.0 + N[(x * N[(N[(x * 0.5), $MachinePrecision] + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 360:\\
\;\;\;\;\frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(x \cdot 0.5 + -1\right)\right)}\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 360

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 88.8%

      \[\leadsto \frac{2}{e^{x} + \color{blue}{\left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)}} \]
    4. Taylor expanded in x around 0 88.4%

      \[\leadsto \frac{2}{\color{blue}{\left(1 + x \cdot \left(1 + 0.5 \cdot x\right)\right)} + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
    5. Step-by-step derivation
      1. *-commutative88.4%

        \[\leadsto \frac{2}{\left(1 + x \cdot \left(1 + \color{blue}{x \cdot 0.5}\right)\right) + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
    6. Simplified88.4%

      \[\leadsto \frac{2}{\color{blue}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right)} + \left(1 + x \cdot \left(x \cdot \left(0.5 + -0.16666666666666666 \cdot x\right) - 1\right)\right)} \]
    7. Taylor expanded in x around 0 83.9%

      \[\leadsto \frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(\color{blue}{0.5 \cdot x} - 1\right)\right)} \]
    8. Step-by-step derivation
      1. *-commutative83.9%

        \[\leadsto \frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(\color{blue}{x \cdot 0.5} - 1\right)\right)} \]
    9. Simplified83.9%

      \[\leadsto \frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(\color{blue}{x \cdot 0.5} - 1\right)\right)} \]

    if 360 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification87.5%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 360:\\ \;\;\;\;\frac{2}{\left(1 + x \cdot \left(1 + x \cdot 0.5\right)\right) + \left(1 + x \cdot \left(x \cdot 0.5 + -1\right)\right)}\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \]
  5. Add Preprocessing

Alternative 7: 74.5% accurate, 17.1× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 1.45:\\ \;\;\;\;1 + \left(x \cdot x\right) \cdot -0.5\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x) :precision binary64 (if (<= x 1.45) (+ 1.0 (* (* x x) -0.5)) 0.0))
double code(double x) {
	double tmp;
	if (x <= 1.45) {
		tmp = 1.0 + ((x * x) * -0.5);
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 1.45d0) then
        tmp = 1.0d0 + ((x * x) * (-0.5d0))
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 1.45) {
		tmp = 1.0 + ((x * x) * -0.5);
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 1.45:
		tmp = 1.0 + ((x * x) * -0.5)
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 1.45)
		tmp = Float64(1.0 + Float64(Float64(x * x) * -0.5));
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 1.45)
		tmp = 1.0 + ((x * x) * -0.5);
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 1.45], N[(1.0 + N[(N[(x * x), $MachinePrecision] * -0.5), $MachinePrecision]), $MachinePrecision], 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 1.45:\\
\;\;\;\;1 + \left(x \cdot x\right) \cdot -0.5\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 1.44999999999999996

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 68.9%

      \[\leadsto \color{blue}{1 + -0.5 \cdot {x}^{2}} \]
    4. Step-by-step derivation
      1. unpow269.7%

        \[\leadsto 1 + {x}^{2} \cdot \left({x}^{2} \cdot \left(0.20833333333333334 + -0.08472222222222223 \cdot \color{blue}{\left(x \cdot x\right)}\right) - 0.5\right) \]
    5. Applied egg-rr68.9%

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

    if 1.44999999999999996 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification76.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq 1.45:\\ \;\;\;\;1 + \left(x \cdot x\right) \cdot -0.5\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \]
  5. Add Preprocessing

Alternative 8: 74.5% accurate, 34.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 350:\\ \;\;\;\;1\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x) :precision binary64 (if (<= x 350.0) 1.0 0.0))
double code(double x) {
	double tmp;
	if (x <= 350.0) {
		tmp = 1.0;
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 350.0d0) then
        tmp = 1.0d0
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 350.0) {
		tmp = 1.0;
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 350.0:
		tmp = 1.0
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 350.0)
		tmp = 1.0;
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 350.0)
		tmp = 1.0;
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 350.0], 1.0, 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 350:\\
\;\;\;\;1\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 350

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Taylor expanded in x around 0 68.4%

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

    if 350 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 9: 34.9% accurate, 34.2× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;x \leq 350:\\ \;\;\;\;0.5\\ \mathbf{else}:\\ \;\;\;\;0\\ \end{array} \end{array} \]
(FPCore (x) :precision binary64 (if (<= x 350.0) 0.5 0.0))
double code(double x) {
	double tmp;
	if (x <= 350.0) {
		tmp = 0.5;
	} else {
		tmp = 0.0;
	}
	return tmp;
}
real(8) function code(x)
    real(8), intent (in) :: x
    real(8) :: tmp
    if (x <= 350.0d0) then
        tmp = 0.5d0
    else
        tmp = 0.0d0
    end if
    code = tmp
end function
public static double code(double x) {
	double tmp;
	if (x <= 350.0) {
		tmp = 0.5;
	} else {
		tmp = 0.0;
	}
	return tmp;
}
def code(x):
	tmp = 0
	if x <= 350.0:
		tmp = 0.5
	else:
		tmp = 0.0
	return tmp
function code(x)
	tmp = 0.0
	if (x <= 350.0)
		tmp = 0.5;
	else
		tmp = 0.0;
	end
	return tmp
end
function tmp_2 = code(x)
	tmp = 0.0;
	if (x <= 350.0)
		tmp = 0.5;
	else
		tmp = 0.0;
	end
	tmp_2 = tmp;
end
code[x_] := If[LessEqual[x, 350.0], 0.5, 0.0]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;x \leq 350:\\
\;\;\;\;0.5\\

\mathbf{else}:\\
\;\;\;\;0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if x < 350

    1. Initial program 99.9%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr14.1%

      \[\leadsto \color{blue}{0.5} \]

    if 350 < x

    1. Initial program 100.0%

      \[\frac{2}{e^{x} + e^{-x}} \]
    2. Add Preprocessing
    3. Applied egg-rr100.0%

      \[\leadsto \color{blue}{0} \]
  3. Recombined 2 regimes into one program.
  4. Add Preprocessing

Alternative 10: 51.7% accurate, 206.0× speedup?

\[\begin{array}{l} \\ 0 \end{array} \]
(FPCore (x) :precision binary64 0.0)
double code(double x) {
	return 0.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = 0.0d0
end function
public static double code(double x) {
	return 0.0;
}
def code(x):
	return 0.0
function code(x)
	return 0.0
end
function tmp = code(x)
	tmp = 0.0;
end
code[x_] := 0.0
\begin{array}{l}

\\
0
\end{array}
Derivation
  1. Initial program 100.0%

    \[\frac{2}{e^{x} + e^{-x}} \]
  2. Add Preprocessing
  3. Applied egg-rr47.4%

    \[\leadsto \color{blue}{0} \]
  4. Add Preprocessing

Reproduce

?
herbie shell --seed 2024150 
(FPCore (x)
  :name "Hyperbolic secant"
  :precision binary64
  (/ 2.0 (+ (exp x) (exp (- x)))))