
(FPCore (x) :precision binary64 (- (/ x (+ x 1.0)) (/ (+ x 1.0) (- x 1.0))))
double code(double x) {
return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = (x / (x + 1.0d0)) - ((x + 1.0d0) / (x - 1.0d0))
end function
public static double code(double x) {
return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0));
}
def code(x): return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0))
function code(x) return Float64(Float64(x / Float64(x + 1.0)) - Float64(Float64(x + 1.0) / Float64(x - 1.0))) end
function tmp = code(x) tmp = (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0)); end
code[x_] := N[(N[(x / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(N[(x + 1.0), $MachinePrecision] / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{x}{x + 1} - \frac{x + 1}{x - 1}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x) :precision binary64 (- (/ x (+ x 1.0)) (/ (+ x 1.0) (- x 1.0))))
double code(double x) {
return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = (x / (x + 1.0d0)) - ((x + 1.0d0) / (x - 1.0d0))
end function
public static double code(double x) {
return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0));
}
def code(x): return (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0))
function code(x) return Float64(Float64(x / Float64(x + 1.0)) - Float64(Float64(x + 1.0) / Float64(x - 1.0))) end
function tmp = code(x) tmp = (x / (x + 1.0)) - ((x + 1.0) / (x - 1.0)); end
code[x_] := N[(N[(x / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(N[(x + 1.0), $MachinePrecision] / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{x}{x + 1} - \frac{x + 1}{x - 1}
\end{array}
(FPCore (x) :precision binary64 (if (<= (+ (/ x (+ x 1.0)) (/ (- -1.0 x) (+ x -1.0))) 1e-5) (/ (+ -3.0 (/ (- -3.0 x) (* x x))) x) (/ (fma x -3.0 -1.0) (fma x x -1.0))))
double code(double x) {
double tmp;
if (((x / (x + 1.0)) + ((-1.0 - x) / (x + -1.0))) <= 1e-5) {
tmp = (-3.0 + ((-3.0 - x) / (x * x))) / x;
} else {
tmp = fma(x, -3.0, -1.0) / fma(x, x, -1.0);
}
return tmp;
}
function code(x) tmp = 0.0 if (Float64(Float64(x / Float64(x + 1.0)) + Float64(Float64(-1.0 - x) / Float64(x + -1.0))) <= 1e-5) tmp = Float64(Float64(-3.0 + Float64(Float64(-3.0 - x) / Float64(x * x))) / x); else tmp = Float64(fma(x, -3.0, -1.0) / fma(x, x, -1.0)); end return tmp end
code[x_] := If[LessEqual[N[(N[(x / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] + N[(N[(-1.0 - x), $MachinePrecision] / N[(x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 1e-5], N[(N[(-3.0 + N[(N[(-3.0 - x), $MachinePrecision] / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / x), $MachinePrecision], N[(N[(x * -3.0 + -1.0), $MachinePrecision] / N[(x * x + -1.0), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{x}{x + 1} + \frac{-1 - x}{x + -1} \leq 10^{-5}:\\
\;\;\;\;\frac{-3 + \frac{-3 - x}{x \cdot x}}{x}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(x, -3, -1\right)}{\mathsf{fma}\left(x, x, -1\right)}\\
\end{array}
\end{array}
if (-.f64 (/.f64 x (+.f64 x #s(literal 1 binary64))) (/.f64 (+.f64 x #s(literal 1 binary64)) (-.f64 x #s(literal 1 binary64)))) < 1.00000000000000008e-5Initial program 8.0%
Taylor expanded in x around inf
Applied rewrites100.0%
Taylor expanded in x around 0
Applied rewrites100.0%
if 1.00000000000000008e-5 < (-.f64 (/.f64 x (+.f64 x #s(literal 1 binary64))) (/.f64 (+.f64 x #s(literal 1 binary64)) (-.f64 x #s(literal 1 binary64)))) Initial program 99.9%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-/.f64N/A
distribute-neg-fracN/A
lift-/.f64N/A
frac-addN/A
*-commutativeN/A
lift-+.f64N/A
lift--.f64N/A
difference-of-sqr-1N/A
metadata-evalN/A
lower-/.f64N/A
Applied rewrites99.9%
Taylor expanded in x around 0
sub-negN/A
metadata-evalN/A
*-commutativeN/A
lower-fma.f64100.0
Applied rewrites100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (if (<= (+ (/ x (+ x 1.0)) (/ (- -1.0 x) (+ x -1.0))) 1e-14) (/ (+ -3.0 (/ -1.0 x)) x) (* (fma x -3.0 -1.0) (/ 1.0 (fma x x -1.0)))))
double code(double x) {
double tmp;
if (((x / (x + 1.0)) + ((-1.0 - x) / (x + -1.0))) <= 1e-14) {
tmp = (-3.0 + (-1.0 / x)) / x;
} else {
tmp = fma(x, -3.0, -1.0) * (1.0 / fma(x, x, -1.0));
}
return tmp;
}
function code(x) tmp = 0.0 if (Float64(Float64(x / Float64(x + 1.0)) + Float64(Float64(-1.0 - x) / Float64(x + -1.0))) <= 1e-14) tmp = Float64(Float64(-3.0 + Float64(-1.0 / x)) / x); else tmp = Float64(fma(x, -3.0, -1.0) * Float64(1.0 / fma(x, x, -1.0))); end return tmp end
code[x_] := If[LessEqual[N[(N[(x / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] + N[(N[(-1.0 - x), $MachinePrecision] / N[(x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 1e-14], N[(N[(-3.0 + N[(-1.0 / x), $MachinePrecision]), $MachinePrecision] / x), $MachinePrecision], N[(N[(x * -3.0 + -1.0), $MachinePrecision] * N[(1.0 / N[(x * x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{x}{x + 1} + \frac{-1 - x}{x + -1} \leq 10^{-14}:\\
\;\;\;\;\frac{-3 + \frac{-1}{x}}{x}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(x, -3, -1\right) \cdot \frac{1}{\mathsf{fma}\left(x, x, -1\right)}\\
\end{array}
\end{array}
if (-.f64 (/.f64 x (+.f64 x #s(literal 1 binary64))) (/.f64 (+.f64 x #s(literal 1 binary64)) (-.f64 x #s(literal 1 binary64)))) < 9.99999999999999999e-15Initial program 7.1%
Taylor expanded in x around inf
associate-*r/N/A
lower-/.f64N/A
neg-mul-1N/A
distribute-neg-inN/A
metadata-evalN/A
lower-+.f64N/A
distribute-neg-fracN/A
metadata-evalN/A
lower-/.f6499.4
Applied rewrites99.4%
if 9.99999999999999999e-15 < (-.f64 (/.f64 x (+.f64 x #s(literal 1 binary64))) (/.f64 (+.f64 x #s(literal 1 binary64)) (-.f64 x #s(literal 1 binary64)))) Initial program 99.1%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-/.f64N/A
distribute-neg-fracN/A
lift-/.f64N/A
frac-addN/A
*-commutativeN/A
lift-+.f64N/A
lift--.f64N/A
difference-of-sqr-1N/A
metadata-evalN/A
lower-/.f64N/A
Applied rewrites99.1%
Taylor expanded in x around 0
sub-negN/A
metadata-evalN/A
*-commutativeN/A
lower-fma.f64100.0
Applied rewrites100.0%
lift-/.f64N/A
div-invN/A
*-commutativeN/A
lower-*.f64N/A
lift-fma.f64N/A
metadata-evalN/A
sub-negN/A
metadata-evalN/A
lower-/.f64N/A
metadata-evalN/A
sub-negN/A
metadata-evalN/A
lift-fma.f64100.0
Applied rewrites100.0%
Final simplification99.7%
herbie shell --seed 2024227
(FPCore (x)
:name "Asymptote C"
:precision binary64
(- (/ x (+ x 1.0)) (/ (+ x 1.0) (- x 1.0))))