
(FPCore (x) :precision binary64 (- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))
double code(double x) {
return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = (1.0d0 / (x + 1.0d0)) - (1.0d0 / (x - 1.0d0))
end function
public static double code(double x) {
return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}
def code(x): return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0))
function code(x) return Float64(Float64(1.0 / Float64(x + 1.0)) - Float64(1.0 / Float64(x - 1.0))) end
function tmp = code(x) tmp = (1.0 / (x + 1.0)) - (1.0 / (x - 1.0)); end
code[x_] := N[(N[(1.0 / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(1.0 / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{x + 1} - \frac{1}{x - 1}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x) :precision binary64 (- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))
double code(double x) {
return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = (1.0d0 / (x + 1.0d0)) - (1.0d0 / (x - 1.0d0))
end function
public static double code(double x) {
return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0));
}
def code(x): return (1.0 / (x + 1.0)) - (1.0 / (x - 1.0))
function code(x) return Float64(Float64(1.0 / Float64(x + 1.0)) - Float64(1.0 / Float64(x - 1.0))) end
function tmp = code(x) tmp = (1.0 / (x + 1.0)) - (1.0 / (x - 1.0)); end
code[x_] := N[(N[(1.0 / N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - N[(1.0 / N[(x - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{x + 1} - \frac{1}{x - 1}
\end{array}
(FPCore (x) :precision binary64 (/ (/ 2.0 (+ 1.0 x)) (- 1.0 x)))
double code(double x) {
return (2.0 / (1.0 + x)) / (1.0 - x);
}
real(8) function code(x)
real(8), intent (in) :: x
code = (2.0d0 / (1.0d0 + x)) / (1.0d0 - x)
end function
public static double code(double x) {
return (2.0 / (1.0 + x)) / (1.0 - x);
}
def code(x): return (2.0 / (1.0 + x)) / (1.0 - x)
function code(x) return Float64(Float64(2.0 / Float64(1.0 + x)) / Float64(1.0 - x)) end
function tmp = code(x) tmp = (2.0 / (1.0 + x)) / (1.0 - x); end
code[x_] := N[(N[(2.0 / N[(1.0 + x), $MachinePrecision]), $MachinePrecision] / N[(1.0 - x), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\frac{2}{1 + x}}{1 - x}
\end{array}
Initial program 75.9%
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-2negN/A
metadata-evalN/A
frac-subN/A
associate-/r*N/A
lower-/.f64N/A
Applied rewrites76.7%
Taylor expanded in x around 0
Applied rewrites99.9%
(FPCore (x) :precision binary64 (if (<= (+ (/ 1.0 (+ 1.0 x)) (/ -1.0 (+ x -1.0))) 0.0) (/ -2.0 (* x x)) (fma 2.0 (* x x) 2.0)))
double code(double x) {
double tmp;
if (((1.0 / (1.0 + x)) + (-1.0 / (x + -1.0))) <= 0.0) {
tmp = -2.0 / (x * x);
} else {
tmp = fma(2.0, (x * x), 2.0);
}
return tmp;
}
function code(x) tmp = 0.0 if (Float64(Float64(1.0 / Float64(1.0 + x)) + Float64(-1.0 / Float64(x + -1.0))) <= 0.0) tmp = Float64(-2.0 / Float64(x * x)); else tmp = fma(2.0, Float64(x * x), 2.0); end return tmp end
code[x_] := If[LessEqual[N[(N[(1.0 / N[(1.0 + x), $MachinePrecision]), $MachinePrecision] + N[(-1.0 / N[(x + -1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 0.0], N[(-2.0 / N[(x * x), $MachinePrecision]), $MachinePrecision], N[(2.0 * N[(x * x), $MachinePrecision] + 2.0), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{1}{1 + x} + \frac{-1}{x + -1} \leq 0:\\
\;\;\;\;\frac{-2}{x \cdot x}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(2, x \cdot x, 2\right)\\
\end{array}
\end{array}
if (-.f64 (/.f64 #s(literal 1 binary64) (+.f64 x #s(literal 1 binary64))) (/.f64 #s(literal 1 binary64) (-.f64 x #s(literal 1 binary64)))) < 0.0Initial program 50.1%
Taylor expanded in x around inf
lower-/.f64N/A
unpow2N/A
lower-*.f6498.1
Applied rewrites98.1%
if 0.0 < (-.f64 (/.f64 #s(literal 1 binary64) (+.f64 x #s(literal 1 binary64))) (/.f64 #s(literal 1 binary64) (-.f64 x #s(literal 1 binary64)))) Initial program 100.0%
Taylor expanded in x around 0
+-commutativeN/A
lower-fma.f64N/A
unpow2N/A
lower-*.f6499.6
Applied rewrites99.6%
Final simplification98.9%
(FPCore (x) :precision binary64 (if (<= x 1.0) (fma 2.0 (* x x) 2.0) (/ 2.0 (- x))))
double code(double x) {
double tmp;
if (x <= 1.0) {
tmp = fma(2.0, (x * x), 2.0);
} else {
tmp = 2.0 / -x;
}
return tmp;
}
function code(x) tmp = 0.0 if (x <= 1.0) tmp = fma(2.0, Float64(x * x), 2.0); else tmp = Float64(2.0 / Float64(-x)); end return tmp end
code[x_] := If[LessEqual[x, 1.0], N[(2.0 * N[(x * x), $MachinePrecision] + 2.0), $MachinePrecision], N[(2.0 / (-x)), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq 1:\\
\;\;\;\;\mathsf{fma}\left(2, x \cdot x, 2\right)\\
\mathbf{else}:\\
\;\;\;\;\frac{2}{-x}\\
\end{array}
\end{array}
if x < 1Initial program 84.0%
Taylor expanded in x around 0
+-commutativeN/A
lower-fma.f64N/A
unpow2N/A
lower-*.f6469.6
Applied rewrites69.6%
if 1 < x Initial program 52.4%
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-2negN/A
metadata-evalN/A
frac-subN/A
associate-/r*N/A
lower-/.f64N/A
Applied rewrites54.8%
Taylor expanded in x around 0
Applied rewrites6.8%
Taylor expanded in x around inf
mul-1-negN/A
lower-neg.f646.8
Applied rewrites6.8%
(FPCore (x) :precision binary64 (/ -2.0 (fma x x -1.0)))
double code(double x) {
return -2.0 / fma(x, x, -1.0);
}
function code(x) return Float64(-2.0 / fma(x, x, -1.0)) end
code[x_] := N[(-2.0 / N[(x * x + -1.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{-2}{\mathsf{fma}\left(x, x, -1\right)}
\end{array}
Initial program 75.9%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-/.f64N/A
distribute-neg-fracN/A
metadata-evalN/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 rewrites76.7%
Taylor expanded in x around 0
Applied rewrites99.3%
(FPCore (x) :precision binary64 (/ 2.0 (- 1.0 x)))
double code(double x) {
return 2.0 / (1.0 - x);
}
real(8) function code(x)
real(8), intent (in) :: x
code = 2.0d0 / (1.0d0 - x)
end function
public static double code(double x) {
return 2.0 / (1.0 - x);
}
def code(x): return 2.0 / (1.0 - x)
function code(x) return Float64(2.0 / Float64(1.0 - x)) end
function tmp = code(x) tmp = 2.0 / (1.0 - x); end
code[x_] := N[(2.0 / N[(1.0 - x), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{2}{1 - x}
\end{array}
Initial program 75.9%
lift--.f64N/A
lift-/.f64N/A
lift-/.f64N/A
frac-2negN/A
metadata-evalN/A
frac-subN/A
associate-/r*N/A
lower-/.f64N/A
Applied rewrites76.7%
Taylor expanded in x around 0
Applied rewrites53.9%
(FPCore (x) :precision binary64 2.0)
double code(double x) {
return 2.0;
}
real(8) function code(x)
real(8), intent (in) :: x
code = 2.0d0
end function
public static double code(double x) {
return 2.0;
}
def code(x): return 2.0
function code(x) return 2.0 end
function tmp = code(x) tmp = 2.0; end
code[x_] := 2.0
\begin{array}{l}
\\
2
\end{array}
Initial program 75.9%
Taylor expanded in x around 0
Applied rewrites52.6%
herbie shell --seed 2024223
(FPCore (x)
:name "Asymptote A"
:precision binary64
(- (/ 1.0 (+ x 1.0)) (/ 1.0 (- x 1.0))))