
(FPCore (x) :precision binary64 (- (log (- (/ 1.0 x) 1.0))))
double code(double x) {
return -log(((1.0 / x) - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = -log(((1.0d0 / x) - 1.0d0))
end function
public static double code(double x) {
return -Math.log(((1.0 / x) - 1.0));
}
def code(x): return -math.log(((1.0 / x) - 1.0))
function code(x) return Float64(-log(Float64(Float64(1.0 / x) - 1.0))) end
function tmp = code(x) tmp = -log(((1.0 / x) - 1.0)); end
code[x_] := (-N[Log[N[(N[(1.0 / x), $MachinePrecision] - 1.0), $MachinePrecision]], $MachinePrecision])
\begin{array}{l}
\\
-\log \left(\frac{1}{x} - 1\right)
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x) :precision binary64 (- (log (- (/ 1.0 x) 1.0))))
double code(double x) {
return -log(((1.0 / x) - 1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = -log(((1.0d0 / x) - 1.0d0))
end function
public static double code(double x) {
return -Math.log(((1.0 / x) - 1.0));
}
def code(x): return -math.log(((1.0 / x) - 1.0))
function code(x) return Float64(-log(Float64(Float64(1.0 / x) - 1.0))) end
function tmp = code(x) tmp = -log(((1.0 / x) - 1.0)); end
code[x_] := (-N[Log[N[(N[(1.0 / x), $MachinePrecision] - 1.0), $MachinePrecision]], $MachinePrecision])
\begin{array}{l}
\\
-\log \left(\frac{1}{x} - 1\right)
\end{array}
(FPCore (x) :precision binary64 (- (log (+ (/ 1.0 x) -1.0))))
double code(double x) {
return -log(((1.0 / x) + -1.0));
}
real(8) function code(x)
real(8), intent (in) :: x
code = -log(((1.0d0 / x) + (-1.0d0)))
end function
public static double code(double x) {
return -Math.log(((1.0 / x) + -1.0));
}
def code(x): return -math.log(((1.0 / x) + -1.0))
function code(x) return Float64(-log(Float64(Float64(1.0 / x) + -1.0))) end
function tmp = code(x) tmp = -log(((1.0 / x) + -1.0)); end
code[x_] := (-N[Log[N[(N[(1.0 / x), $MachinePrecision] + -1.0), $MachinePrecision]], $MachinePrecision])
\begin{array}{l}
\\
-\log \left(\frac{1}{x} + -1\right)
\end{array}
Initial program 100.0%
Final simplification100.0%
(FPCore (x) :precision binary64 (fma x (fma x 0.5 1.0) (log x)))
double code(double x) {
return fma(x, fma(x, 0.5, 1.0), log(x));
}
function code(x) return fma(x, fma(x, 0.5, 1.0), log(x)) end
code[x_] := N[(x * N[(x * 0.5 + 1.0), $MachinePrecision] + N[Log[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(x, \mathsf{fma}\left(x, 0.5, 1\right), \log x\right)
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
lower-log.f6499.6
Applied rewrites99.6%
(FPCore (x) :precision binary64 (+ x (log x)))
double code(double x) {
return x + log(x);
}
real(8) function code(x)
real(8), intent (in) :: x
code = x + log(x)
end function
public static double code(double x) {
return x + Math.log(x);
}
def code(x): return x + math.log(x)
function code(x) return Float64(x + log(x)) end
function tmp = code(x) tmp = x + log(x); end
code[x_] := N[(x + N[Log[x], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x + \log x
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
sub-negN/A
mul-1-negN/A
remove-double-negN/A
lower-+.f64N/A
lower-log.f6499.3
Applied rewrites99.3%
(FPCore (x) :precision binary64 (log x))
double code(double x) {
return log(x);
}
real(8) function code(x)
real(8), intent (in) :: x
code = log(x)
end function
public static double code(double x) {
return Math.log(x);
}
def code(x): return math.log(x)
function code(x) return log(x) end
function tmp = code(x) tmp = log(x); end
code[x_] := N[Log[x], $MachinePrecision]
\begin{array}{l}
\\
\log x
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
lower-log.f6498.1
Applied rewrites98.1%
(FPCore (x)
:precision binary64
(if (<= (/ 1.0 x) 5e+106)
(/
(* (fma x (* (* x x) 0.125) 1.0) (* x (* x x)))
(* (* x x) (* x (fma x 0.25 -0.5))))
(/ 0.5 (/ 1.0 (* x x)))))
double code(double x) {
double tmp;
if ((1.0 / x) <= 5e+106) {
tmp = (fma(x, ((x * x) * 0.125), 1.0) * (x * (x * x))) / ((x * x) * (x * fma(x, 0.25, -0.5)));
} else {
tmp = 0.5 / (1.0 / (x * x));
}
return tmp;
}
function code(x) tmp = 0.0 if (Float64(1.0 / x) <= 5e+106) tmp = Float64(Float64(fma(x, Float64(Float64(x * x) * 0.125), 1.0) * Float64(x * Float64(x * x))) / Float64(Float64(x * x) * Float64(x * fma(x, 0.25, -0.5)))); else tmp = Float64(0.5 / Float64(1.0 / Float64(x * x))); end return tmp end
code[x_] := If[LessEqual[N[(1.0 / x), $MachinePrecision], 5e+106], N[(N[(N[(x * N[(N[(x * x), $MachinePrecision] * 0.125), $MachinePrecision] + 1.0), $MachinePrecision] * N[(x * N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(x * x), $MachinePrecision] * N[(x * N[(x * 0.25 + -0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(0.5 / N[(1.0 / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{1}{x} \leq 5 \cdot 10^{+106}:\\
\;\;\;\;\frac{\mathsf{fma}\left(x, \left(x \cdot x\right) \cdot 0.125, 1\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{\left(x \cdot x\right) \cdot \left(x \cdot \mathsf{fma}\left(x, 0.25, -0.5\right)\right)}\\
\mathbf{else}:\\
\;\;\;\;\frac{0.5}{\frac{1}{x \cdot x}}\\
\end{array}
\end{array}
if (/.f64 #s(literal 1 binary64) x) < 4.9999999999999998e106Initial program 100.0%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
lower-log.f6498.9
Applied rewrites98.9%
Taylor expanded in x around inf
Applied rewrites1.9%
Applied rewrites1.9%
Taylor expanded in x around inf
Applied rewrites14.8%
if 4.9999999999999998e106 < (/.f64 #s(literal 1 binary64) x) Initial program 100.0%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
lower-log.f64100.0
Applied rewrites100.0%
Applied rewrites100.0%
Taylor expanded in x around inf
Applied rewrites3.0%
Applied rewrites3.0%
(FPCore (x) :precision binary64 (/ 0.5 (/ 1.0 (* x x))))
double code(double x) {
return 0.5 / (1.0 / (x * x));
}
real(8) function code(x)
real(8), intent (in) :: x
code = 0.5d0 / (1.0d0 / (x * x))
end function
public static double code(double x) {
return 0.5 / (1.0 / (x * x));
}
def code(x): return 0.5 / (1.0 / (x * x))
function code(x) return Float64(0.5 / Float64(1.0 / Float64(x * x))) end
function tmp = code(x) tmp = 0.5 / (1.0 / (x * x)); end
code[x_] := N[(0.5 / N[(1.0 / N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{0.5}{\frac{1}{x \cdot x}}
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
lower-log.f6499.6
Applied rewrites99.6%
Applied rewrites99.6%
Taylor expanded in x around inf
Applied rewrites2.7%
Applied rewrites2.7%
(FPCore (x) :precision binary64 (* x (* x 0.5)))
double code(double x) {
return x * (x * 0.5);
}
real(8) function code(x)
real(8), intent (in) :: x
code = x * (x * 0.5d0)
end function
public static double code(double x) {
return x * (x * 0.5);
}
def code(x): return x * (x * 0.5)
function code(x) return Float64(x * Float64(x * 0.5)) end
function tmp = code(x) tmp = x * (x * 0.5); end
code[x_] := N[(x * N[(x * 0.5), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x \cdot \left(x \cdot 0.5\right)
\end{array}
Initial program 100.0%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
lower-log.f6499.6
Applied rewrites99.6%
Taylor expanded in x around inf
Applied rewrites2.7%
herbie shell --seed 2024234
(FPCore (x)
:name "neg log"
:precision binary64
(- (log (- (/ 1.0 x) 1.0))))