
(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 5 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 (* (log u1) -0.05555555555555555)) (cos (* u2 (* (PI) 2.0))) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\sqrt{\log u1 \cdot -0.05555555555555555}, \cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right), 0.5\right)
\end{array}
Initial program 99.3%
lift-pow.f64N/A
pow-to-expN/A
lower-exp.f64N/A
lower-*.f64N/A
lower-log.f6498.9
lift-*.f64N/A
*-commutativeN/A
lower-*.f6498.9
Applied rewrites98.9%
Applied rewrites99.7%
lift-+.f64N/A
Applied rewrites99.7%
Final simplification99.7%
(FPCore (u1 u2) :precision binary64 (- 0.5 (* (* (/ -1.0 6.0) (* (sqrt (- (log u1))) (sqrt 2.0))) (fma (* (* u2 u2) -2.0) (* (PI) (PI)) 1.0))))
\begin{array}{l}
\\
0.5 - \left(\frac{-1}{6} \cdot \left(\sqrt{-\log u1} \cdot \sqrt{2}\right)\right) \cdot \mathsf{fma}\left(\left(u2 \cdot u2\right) \cdot -2, \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 1\right)
\end{array}
Initial program 99.3%
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.f6499.4
Applied rewrites99.4%
Taylor expanded in u2 around 0
+-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
lower-PI.f64N/A
lower-PI.f6498.9
Applied rewrites98.9%
Final simplification98.9%
(FPCore (u1 u2) :precision binary64 (fma (* 0.16666666666666666 (fma (* (* u2 u2) -2.0) (* (PI) (PI)) 1.0)) (sqrt (* -2.0 (log u1))) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(0.16666666666666666 \cdot \mathsf{fma}\left(\left(u2 \cdot u2\right) \cdot -2, \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 1\right), \sqrt{-2 \cdot \log u1}, 0.5\right)
\end{array}
Initial program 99.3%
lift-+.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-fma.f64N/A
Applied rewrites99.3%
Taylor expanded in u2 around 0
+-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
lower-PI.f64N/A
lower-PI.f6498.8
Applied rewrites98.8%
Final simplification98.8%
(FPCore (u1 u2) :precision binary64 (fma (fma (* -0.3333333333333333 (* u2 u2)) (* (PI) (PI)) 0.16666666666666666) (sqrt (* -2.0 (log u1))) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\mathsf{fma}\left(-0.3333333333333333 \cdot \left(u2 \cdot u2\right), \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 0.16666666666666666\right), \sqrt{-2 \cdot \log u1}, 0.5\right)
\end{array}
Initial program 99.3%
lift-+.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-fma.f64N/A
Applied rewrites99.3%
Taylor expanded in u2 around 0
+-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
unpow2N/A
lower-*.f64N/A
lower-PI.f64N/A
lower-PI.f6498.8
Applied rewrites98.8%
Final simplification98.8%
(FPCore (u1 u2) :precision binary64 (- (sqrt (* (log u1) -0.05555555555555555)) -0.5))
double code(double u1, double u2) {
return sqrt((log(u1) * -0.05555555555555555)) - -0.5;
}
real(8) function code(u1, u2)
real(8), intent (in) :: u1
real(8), intent (in) :: u2
code = sqrt((log(u1) * (-0.05555555555555555d0))) - (-0.5d0)
end function
public static double code(double u1, double u2) {
return Math.sqrt((Math.log(u1) * -0.05555555555555555)) - -0.5;
}
def code(u1, u2): return math.sqrt((math.log(u1) * -0.05555555555555555)) - -0.5
function code(u1, u2) return Float64(sqrt(Float64(log(u1) * -0.05555555555555555)) - -0.5) end
function tmp = code(u1, u2) tmp = sqrt((log(u1) * -0.05555555555555555)) - -0.5; end
code[u1_, u2_] := N[(N[Sqrt[N[(N[Log[u1], $MachinePrecision] * -0.05555555555555555), $MachinePrecision]], $MachinePrecision] - -0.5), $MachinePrecision]
\begin{array}{l}
\\
\sqrt{\log u1 \cdot -0.05555555555555555} - -0.5
\end{array}
Initial program 99.3%
Taylor expanded in u2 around 0
+-commutativeN/A
*-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
lower-sqrt.f64N/A
lower-sqrt.f64N/A
lower-log.f640.0
Applied rewrites0.0%
Applied rewrites98.4%
Applied rewrites98.7%
Final simplification98.7%
herbie shell --seed 2024298
(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))