
(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 3 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 (* (* 2.0 (PI)) u2)) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\sqrt{-0.05555555555555555 \cdot \log u1}, \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right), 0.5\right)
\end{array}
Initial program 99.4%
lift-+.f64N/A
lift-*.f64N/A
lower-fma.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-pow.f64N/A
unpow1/2N/A
lower-sqrt.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-/.f64N/A
metadata-eval99.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.4
Applied rewrites99.4%
Applied rewrites99.3%
unpow1N/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
unpow2N/A
lift-pow.f64N/A
lower-pow.f6499.3
lift-pow.f64N/A
lift-*.f64N/A
*-commutativeN/A
unpow-prod-downN/A
lower-*.f64N/A
metadata-evalN/A
lift-sqrt.f64N/A
sqrt-pow2N/A
metadata-evalN/A
unpow199.5
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.5
Applied rewrites99.5%
lift-/.f64N/A
lift-/.f64N/A
remove-double-div99.6
lift-pow.f64N/A
unpow1/2N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
metadata-evalN/A
lower-sqrt.f64N/A
lower-*.f6499.6
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.6
lift-*.f64N/A
*-commutativeN/A
lower-*.f6499.6
Applied rewrites99.6%
(FPCore (u1 u2) :precision binary64 (+ (* (* (pow 6.0 -1.0) (* (sqrt 2.0) (sqrt (- (log u1))))) (fma (* (* (PI) (PI)) -2.0) (* u2 u2) 1.0)) 0.5))
\begin{array}{l}
\\
\left({6}^{-1} \cdot \left(\sqrt{2} \cdot \sqrt{-\log u1}\right)\right) \cdot \mathsf{fma}\left(\left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) \cdot -2, u2 \cdot u2, 1\right) + 0.5
\end{array}
Initial program 99.4%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
log-recN/A
lower-neg.f64N/A
lower-log.f6499.5
Applied rewrites99.5%
Taylor expanded in u2 around 0
+-commutativeN/A
rem-square-sqrtN/A
unpow2N/A
*-commutativeN/A
associate-*r*N/A
unpow2N/A
rem-square-sqrtN/A
lower-fma.f64N/A
*-commutativeN/A
rem-square-sqrtN/A
unpow2N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
lower-PI.f64N/A
lower-PI.f64N/A
unpow2N/A
rem-square-sqrtN/A
unpow2N/A
lower-*.f6498.4
Applied rewrites98.4%
Final simplification98.4%
(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%
Taylor expanded in u2 around 0
+-commutativeN/A
*-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-log.f640.0
Applied rewrites0.0%
Applied rewrites97.2%
Applied rewrites97.2%
Applied rewrites97.4%
herbie shell --seed 2024319
(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))