
(FPCore (u1 u2) :precision binary64 (+ (* (* (/ 1.0 6.0) (pow (* -2.0 (log u1)) 0.5)) (cos (* (* 2.0 (PI)) u2))) 0.5))
\begin{array}{l}
\\
\left(\frac{1}{6} \cdot {\left(-2 \cdot \log u1\right)}^{0.5}\right) \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) + 0.5
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 2 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (u1 u2) :precision binary64 (+ (* (* (/ 1.0 6.0) (pow (* -2.0 (log u1)) 0.5)) (cos (* (* 2.0 (PI)) u2))) 0.5))
\begin{array}{l}
\\
\left(\frac{1}{6} \cdot {\left(-2 \cdot \log u1\right)}^{0.5}\right) \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right) + 0.5
\end{array}
(FPCore (u1 u2) :precision binary64 (fma (sqrt (* -0.05555555555555555 (log u1))) (cos (* (* (PI) 2.0) u2)) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\sqrt{-0.05555555555555555 \cdot \log u1}, \cos \left(\left(\mathsf{PI}\left(\right) \cdot 2\right) \cdot u2\right), 0.5\right)
\end{array}
Initial program 99.4%
lift-pow.f64N/A
unpow1/2N/A
lower-sqrt.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
Applied rewrites99.4%
lift-*.f64N/A
lift-/.f64N/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lift-/.f64N/A
lift-sqrt.f64N/A
pow1/2N/A
metadata-evalN/A
pow-powN/A
lift-pow.f64N/A
sqr-powN/A
sqr-abs-revN/A
mul-fabsN/A
sqr-powN/A
lift-pow.f64N/A
pow-powN/A
metadata-evalN/A
pow1/2N/A
lift-sqrt.f64N/A
Applied rewrites99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-sqrt.f64N/A
lift-*.f64N/A
sqrt-prodN/A
metadata-evalN/A
lift-sqrt.f64N/A
*-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
lift-*.f64N/A
Applied rewrites99.6%
(FPCore (u1 u2) :precision binary64 (+ (sqrt (* -0.05555555555555555 (log u1))) 0.5))
double code(double u1, double u2) {
return sqrt((-0.05555555555555555 * log(u1))) + 0.5;
}
real(8) function code(u1, u2)
real(8), intent (in) :: u1
real(8), intent (in) :: u2
code = sqrt(((-0.05555555555555555d0) * log(u1))) + 0.5d0
end function
public static double code(double u1, double u2) {
return Math.sqrt((-0.05555555555555555 * Math.log(u1))) + 0.5;
}
def code(u1, u2): return math.sqrt((-0.05555555555555555 * math.log(u1))) + 0.5
function code(u1, u2) return Float64(sqrt(Float64(-0.05555555555555555 * log(u1))) + 0.5) end
function tmp = code(u1, u2) tmp = sqrt((-0.05555555555555555 * log(u1))) + 0.5; end
code[u1_, u2_] := N[(N[Sqrt[N[(-0.05555555555555555 * N[Log[u1], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + 0.5), $MachinePrecision]
\begin{array}{l}
\\
\sqrt{-0.05555555555555555 \cdot \log u1} + 0.5
\end{array}
Initial program 99.4%
Applied rewrites98.4%
lift-sqrt.f64N/A
lift-*.f64N/A
*-commutativeN/A
metadata-evalN/A
distribute-lft-neg-inN/A
distribute-rgt-neg-outN/A
lift-neg.f64N/A
*-commutativeN/A
sqrt-unprodN/A
lift-sqrt.f64N/A
pow1/2N/A
sqr-powN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-downN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-downN/A
pow-sqrN/A
metadata-evalN/A
metadata-evalN/A
lower-*.f64N/A
Applied rewrites98.5%
lift-*.f64N/A
lift-sqrt.f64N/A
lift-sqrt.f64N/A
sqrt-unprodN/A
lift-neg.f64N/A
distribute-lft-neg-outN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
lift-*.f64N/A
lift-sqrt.f6498.4
lower-fma.f64N/A
lift-*.f64N/A
lower-+.f6498.4
Applied rewrites98.6%
herbie shell --seed 2024340
(FPCore (u1 u2)
:name "normal distribution"
:precision binary64
:pre (and (and (<= 0.0 u1) (<= u1 1.0)) (and (<= 0.0 u2) (<= u2 1.0)))
(+ (* (* (/ 1.0 6.0) (pow (* -2.0 (log u1)) 0.5)) (cos (* (* 2.0 (PI)) u2))) 0.5))