Hyperbolic sine

Percentage Accurate: 53.8% → 100.0%
Time: 12.0s
Alternatives: 16
Speedup: 12.8×

Specification

?
\[\begin{array}{l} \\ \frac{e^{x} - e^{-x}}{2} \end{array} \]
(FPCore (x) :precision binary64 (/ (- (exp x) (exp (- x))) 2.0))
double code(double x) {
	return (exp(x) - exp(-x)) / 2.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = (exp(x) - exp(-x)) / 2.0d0
end function
public static double code(double x) {
	return (Math.exp(x) - Math.exp(-x)) / 2.0;
}
def code(x):
	return (math.exp(x) - math.exp(-x)) / 2.0
function code(x)
	return Float64(Float64(exp(x) - exp(Float64(-x))) / 2.0)
end
function tmp = code(x)
	tmp = (exp(x) - exp(-x)) / 2.0;
end
code[x_] := N[(N[(N[Exp[x], $MachinePrecision] - N[Exp[(-x)], $MachinePrecision]), $MachinePrecision] / 2.0), $MachinePrecision]
\begin{array}{l}

\\
\frac{e^{x} - e^{-x}}{2}
\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 16 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: 53.8% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \frac{e^{x} - e^{-x}}{2} \end{array} \]
(FPCore (x) :precision binary64 (/ (- (exp x) (exp (- x))) 2.0))
double code(double x) {
	return (exp(x) - exp(-x)) / 2.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = (exp(x) - exp(-x)) / 2.0d0
end function
public static double code(double x) {
	return (Math.exp(x) - Math.exp(-x)) / 2.0;
}
def code(x):
	return (math.exp(x) - math.exp(-x)) / 2.0
function code(x)
	return Float64(Float64(exp(x) - exp(Float64(-x))) / 2.0)
end
function tmp = code(x)
	tmp = (exp(x) - exp(-x)) / 2.0;
end
code[x_] := N[(N[(N[Exp[x], $MachinePrecision] - N[Exp[(-x)], $MachinePrecision]), $MachinePrecision] / 2.0), $MachinePrecision]
\begin{array}{l}

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

Alternative 1: 100.0% accurate, 2.1× speedup?

\[\begin{array}{l} \\ \sinh x \end{array} \]
(FPCore (x) :precision binary64 (sinh x))
double code(double x) {
	return sinh(x);
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = sinh(x)
end function
public static double code(double x) {
	return Math.sinh(x);
}
def code(x):
	return math.sinh(x)
function code(x)
	return sinh(x)
end
function tmp = code(x)
	tmp = sinh(x);
end
code[x_] := N[Sinh[x], $MachinePrecision]
\begin{array}{l}

\\
\sinh x
\end{array}
Derivation
  1. Initial program 52.7%

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

      \[\leadsto \color{blue}{\frac{e^{x} - e^{\mathsf{neg}\left(x\right)}}{2}} \]
    2. lift--.f64N/A

      \[\leadsto \frac{\color{blue}{e^{x} - e^{\mathsf{neg}\left(x\right)}}}{2} \]
    3. lift-exp.f64N/A

      \[\leadsto \frac{\color{blue}{e^{x}} - e^{\mathsf{neg}\left(x\right)}}{2} \]
    4. lift-exp.f64N/A

      \[\leadsto \frac{e^{x} - \color{blue}{e^{\mathsf{neg}\left(x\right)}}}{2} \]
    5. lift-neg.f64N/A

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

      \[\leadsto \color{blue}{\sinh x} \]
    7. lower-sinh.f64100.0

      \[\leadsto \color{blue}{\sinh x} \]
  4. Applied rewrites100.0%

    \[\leadsto \color{blue}{\sinh x} \]
  5. Add Preprocessing

Alternative 2: 91.6% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;e^{x} - e^{-x} \leq 0.002:\\ \;\;\;\;\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot \mathsf{fma}\left(x, x \cdot 0.008333333333333333, 0.16666666666666666\right), x\right)\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\left(x \cdot \left(x \cdot x\right)\right) \cdot \left(x \cdot \mathsf{fma}\left(x \cdot x, 0.0001984126984126984, 0.008333333333333333\right)\right)\right)\\ \end{array} \end{array} \]
(FPCore (x)
 :precision binary64
 (if (<= (- (exp x) (exp (- x))) 0.002)
   (fma x (* (* x x) (fma x (* x 0.008333333333333333) 0.16666666666666666)) x)
   (*
    x
    (*
     (* x (* x x))
     (* x (fma (* x x) 0.0001984126984126984 0.008333333333333333))))))
double code(double x) {
	double tmp;
	if ((exp(x) - exp(-x)) <= 0.002) {
		tmp = fma(x, ((x * x) * fma(x, (x * 0.008333333333333333), 0.16666666666666666)), x);
	} else {
		tmp = x * ((x * (x * x)) * (x * fma((x * x), 0.0001984126984126984, 0.008333333333333333)));
	}
	return tmp;
}
function code(x)
	tmp = 0.0
	if (Float64(exp(x) - exp(Float64(-x))) <= 0.002)
		tmp = fma(x, Float64(Float64(x * x) * fma(x, Float64(x * 0.008333333333333333), 0.16666666666666666)), x);
	else
		tmp = Float64(x * Float64(Float64(x * Float64(x * x)) * Float64(x * fma(Float64(x * x), 0.0001984126984126984, 0.008333333333333333))));
	end
	return tmp
end
code[x_] := If[LessEqual[N[(N[Exp[x], $MachinePrecision] - N[Exp[(-x)], $MachinePrecision]), $MachinePrecision], 0.002], N[(x * N[(N[(x * x), $MachinePrecision] * N[(x * N[(x * 0.008333333333333333), $MachinePrecision] + 0.16666666666666666), $MachinePrecision]), $MachinePrecision] + x), $MachinePrecision], N[(x * N[(N[(x * N[(x * x), $MachinePrecision]), $MachinePrecision] * N[(x * N[(N[(x * x), $MachinePrecision] * 0.0001984126984126984 + 0.008333333333333333), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;e^{x} - e^{-x} \leq 0.002:\\
\;\;\;\;\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot \mathsf{fma}\left(x, x \cdot 0.008333333333333333, 0.16666666666666666\right), x\right)\\

\mathbf{else}:\\
\;\;\;\;x \cdot \left(\left(x \cdot \left(x \cdot x\right)\right) \cdot \left(x \cdot \mathsf{fma}\left(x \cdot x, 0.0001984126984126984, 0.008333333333333333\right)\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (-.f64 (exp.f64 x) (exp.f64 (neg.f64 x))) < 2e-3

    1. Initial program 38.9%

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

      \[\leadsto \color{blue}{x \cdot \left(1 + {x}^{2} \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right)\right)} \]
    4. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{\left(1 + {x}^{2} \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right)\right) \cdot x} \]
      2. +-commutativeN/A

        \[\leadsto \color{blue}{\left({x}^{2} \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right) + 1\right)} \cdot x \]
      3. distribute-lft1-inN/A

        \[\leadsto \color{blue}{\left({x}^{2} \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right)\right) \cdot x + x} \]
      4. associate-*l*N/A

        \[\leadsto \color{blue}{{x}^{2} \cdot \left(\left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right) \cdot x\right)} + x \]
      5. lower-fma.f64N/A

        \[\leadsto \color{blue}{\mathsf{fma}\left({x}^{2}, \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right) \cdot x, x\right)} \]
      6. unpow2N/A

        \[\leadsto \mathsf{fma}\left(\color{blue}{x \cdot x}, \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right) \cdot x, x\right) \]
      7. lower-*.f64N/A

        \[\leadsto \mathsf{fma}\left(\color{blue}{x \cdot x}, \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right) \cdot x, x\right) \]
      8. *-commutativeN/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, \color{blue}{x \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right)}, x\right) \]
      9. lower-*.f64N/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, \color{blue}{x \cdot \left(\frac{1}{6} + \frac{1}{120} \cdot {x}^{2}\right)}, x\right) \]
      10. +-commutativeN/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \color{blue}{\left(\frac{1}{120} \cdot {x}^{2} + \frac{1}{6}\right)}, x\right) \]
      11. *-commutativeN/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \left(\color{blue}{{x}^{2} \cdot \frac{1}{120}} + \frac{1}{6}\right), x\right) \]
      12. unpow2N/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \left(\color{blue}{\left(x \cdot x\right)} \cdot \frac{1}{120} + \frac{1}{6}\right), x\right) \]
      13. associate-*l*N/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \left(\color{blue}{x \cdot \left(x \cdot \frac{1}{120}\right)} + \frac{1}{6}\right), x\right) \]
      14. lower-fma.f64N/A

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \color{blue}{\mathsf{fma}\left(x, x \cdot \frac{1}{120}, \frac{1}{6}\right)}, x\right) \]
      15. lower-*.f6493.6

        \[\leadsto \mathsf{fma}\left(x \cdot x, x \cdot \mathsf{fma}\left(x, \color{blue}{x \cdot 0.008333333333333333}, 0.16666666666666666\right), x\right) \]
    5. Applied rewrites93.6%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x \cdot x, x \cdot \mathsf{fma}\left(x, x \cdot 0.008333333333333333, 0.16666666666666666\right), x\right)} \]
    6. Step-by-step derivation
      1. Applied rewrites93.6%

        \[\leadsto \mathsf{fma}\left(x, \color{blue}{\mathsf{fma}\left(x, x \cdot 0.008333333333333333, 0.16666666666666666\right) \cdot \left(x \cdot x\right)}, x\right) \]

      if 2e-3 < (-.f64 (exp.f64 x) (exp.f64 (neg.f64 x)))

      1. Initial program 100.0%

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

        \[\leadsto \color{blue}{x \cdot \left(1 + {x}^{2} \cdot \left(\frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right)\right)\right)} \]
      4. Step-by-step derivation
        1. lower-*.f64N/A

          \[\leadsto \color{blue}{x \cdot \left(1 + {x}^{2} \cdot \left(\frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right)\right)\right)} \]
        2. +-commutativeN/A

          \[\leadsto x \cdot \color{blue}{\left({x}^{2} \cdot \left(\frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right)\right) + 1\right)} \]
        3. lower-fma.f64N/A

          \[\leadsto x \cdot \color{blue}{\mathsf{fma}\left({x}^{2}, \frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right), 1\right)} \]
        4. unpow2N/A

          \[\leadsto x \cdot \mathsf{fma}\left(\color{blue}{x \cdot x}, \frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right), 1\right) \]
        5. lower-*.f64N/A

          \[\leadsto x \cdot \mathsf{fma}\left(\color{blue}{x \cdot x}, \frac{1}{6} + {x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right), 1\right) \]
        6. +-commutativeN/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \color{blue}{{x}^{2} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right) + \frac{1}{6}}, 1\right) \]
        7. unpow2N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \color{blue}{\left(x \cdot x\right)} \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right) + \frac{1}{6}, 1\right) \]
        8. associate-*l*N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \color{blue}{x \cdot \left(x \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right)\right)} + \frac{1}{6}, 1\right) \]
        9. lower-fma.f64N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \color{blue}{\mathsf{fma}\left(x, x \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right), \frac{1}{6}\right)}, 1\right) \]
        10. lower-*.f64N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, \color{blue}{x \cdot \left(\frac{1}{120} + \frac{1}{5040} \cdot {x}^{2}\right)}, \frac{1}{6}\right), 1\right) \]
        11. +-commutativeN/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \color{blue}{\left(\frac{1}{5040} \cdot {x}^{2} + \frac{1}{120}\right)}, \frac{1}{6}\right), 1\right) \]
        12. *-commutativeN/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \left(\color{blue}{{x}^{2} \cdot \frac{1}{5040}} + \frac{1}{120}\right), \frac{1}{6}\right), 1\right) \]
        13. unpow2N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \left(\color{blue}{\left(x \cdot x\right)} \cdot \frac{1}{5040} + \frac{1}{120}\right), \frac{1}{6}\right), 1\right) \]
        14. associate-*l*N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \left(\color{blue}{x \cdot \left(x \cdot \frac{1}{5040}\right)} + \frac{1}{120}\right), \frac{1}{6}\right), 1\right) \]
        15. lower-fma.f64N/A

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \color{blue}{\mathsf{fma}\left(x, x \cdot \frac{1}{5040}, \frac{1}{120}\right)}, \frac{1}{6}\right), 1\right) \]
        16. lower-*.f6486.3

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \mathsf{fma}\left(x, \color{blue}{x \cdot 0.0001984126984126984}, 0.008333333333333333\right), 0.16666666666666666\right), 1\right) \]
      5. Applied rewrites86.3%

        \[\leadsto \color{blue}{x \cdot \mathsf{fma}\left(x \cdot x, \mathsf{fma}\left(x, x \cdot \mathsf{fma}\left(x, x \cdot 0.0001984126984126984, 0.008333333333333333\right), 0.16666666666666666\right), 1\right)} \]
      6. Step-by-step derivation
        1. Applied rewrites86.3%

          \[\leadsto x \cdot \mathsf{fma}\left(x \cdot x, x \cdot \left(x \cdot \mathsf{fma}\left(x \cdot x, 0.0001984126984126984, 0.008333333333333333\right)\right) + \color{blue}{0.16666666666666666}, 1\right) \]
        2. Taylor expanded in x around inf

          \[\leadsto x \cdot \left({x}^{6} \cdot \color{blue}{\left(\frac{1}{5040} + \frac{1}{120} \cdot \frac{1}{{x}^{2}}\right)}\right) \]
        3. Applied rewrites85.4%

          \[\leadsto x \cdot \left(\left(x \cdot \left(x \cdot x\right)\right) \cdot \color{blue}{\left(x \cdot \mathsf{fma}\left(x \cdot x, 0.0001984126984126984, 0.008333333333333333\right)\right)}\right) \]
      7. Recombined 2 regimes into one program.
      8. Final simplification91.6%

        \[\leadsto \begin{array}{l} \mathbf{if}\;e^{x} - e^{-x} \leq 0.002:\\ \;\;\;\;\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot \mathsf{fma}\left(x, x \cdot 0.008333333333333333, 0.16666666666666666\right), x\right)\\ \mathbf{else}:\\ \;\;\;\;x \cdot \left(\left(x \cdot \left(x \cdot x\right)\right) \cdot \left(x \cdot \mathsf{fma}\left(x \cdot x, 0.0001984126984126984, 0.008333333333333333\right)\right)\right)\\ \end{array} \]
      9. Add Preprocessing

      Reproduce

      ?
      herbie shell --seed 2024219 
      (FPCore (x)
        :name "Hyperbolic sine"
        :precision binary64
        (/ (- (exp x) (exp (- x))) 2.0))