
(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 6 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))) (sqrt 2.0)) 0.16666666666666666) (cos (* u2 (* (PI) 2.0))) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\left(\sqrt{-\log u1} \cdot \sqrt{2}\right) \cdot 0.16666666666666666, \cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\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%
lift-sqrt.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-log.f64N/A
metadata-evalN/A
lift-log.f64N/A
associate-*r*N/A
neg-mul-1N/A
lift-neg.f64N/A
*-commutativeN/A
sqrt-unprodN/A
lift-sqrt.f64N/A
lift-sqrt.f64N/A
lower-*.f6499.5
Applied rewrites99.5%
(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-*.f6499.1
Applied rewrites99.1%
Final simplification99.1%
(FPCore (u1 u2) :precision binary64 (fma (* (cos (* u2 (* (PI) 2.0))) 0.16666666666666666) (sqrt (* (log u1) -2.0)) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot 0.16666666666666666, \sqrt{\log u1 \cdot -2}, 0.5\right)
\end{array}
Initial program 99.4%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
*-commutativeN/A
associate-*r*N/A
lower-fma.f64N/A
Applied rewrites99.4%
(FPCore (u1 u2) :precision binary64 (fma (fma (* (* u2 u2) -0.3333333333333333) (* (PI) (PI)) 0.16666666666666666) (sqrt (* -2.0 (log u1))) 0.5))
\begin{array}{l}
\\
\mathsf{fma}\left(\mathsf{fma}\left(\left(u2 \cdot u2\right) \cdot -0.3333333333333333, \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right), 0.16666666666666666\right), \sqrt{-2 \cdot \log u1}, 0.5\right)
\end{array}
Initial program 99.4%
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%
metadata-evalN/A
lift-fma.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
lower-fma.f64N/A
Applied rewrites99.3%
lift-fma.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-sqrt.f64N/A
pow1/2N/A
lift-*.f64N/A
*-commutativeN/A
lift-log.f64N/A
lift-cos.f64N/A
lift-*.f64N/A
lift-*.f64N/A
*-commutativeN/A
lift-PI.f64N/A
*-commutativeN/A
associate-*l*N/A
Applied rewrites99.4%
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.f6499.0
Applied rewrites99.0%
(FPCore (u1 u2) :precision binary64 (+ (* (* 0.16666666666666666 (* (sqrt 2.0) (sqrt (- (log u1))))) 1.0) 0.5))
double code(double u1, double u2) {
return ((0.16666666666666666 * (sqrt(2.0) * sqrt(-log(u1)))) * 1.0) + 0.5;
}
real(8) function code(u1, u2)
real(8), intent (in) :: u1
real(8), intent (in) :: u2
code = ((0.16666666666666666d0 * (sqrt(2.0d0) * sqrt(-log(u1)))) * 1.0d0) + 0.5d0
end function
public static double code(double u1, double u2) {
return ((0.16666666666666666 * (Math.sqrt(2.0) * Math.sqrt(-Math.log(u1)))) * 1.0) + 0.5;
}
def code(u1, u2): return ((0.16666666666666666 * (math.sqrt(2.0) * math.sqrt(-math.log(u1)))) * 1.0) + 0.5
function code(u1, u2) return Float64(Float64(Float64(0.16666666666666666 * Float64(sqrt(2.0) * sqrt(Float64(-log(u1))))) * 1.0) + 0.5) end
function tmp = code(u1, u2) tmp = ((0.16666666666666666 * (sqrt(2.0) * sqrt(-log(u1)))) * 1.0) + 0.5; end
code[u1_, u2_] := N[(N[(N[(0.16666666666666666 * N[(N[Sqrt[2.0], $MachinePrecision] * N[Sqrt[(-N[Log[u1], $MachinePrecision])], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] * 1.0), $MachinePrecision] + 0.5), $MachinePrecision]
\begin{array}{l}
\\
\left(0.16666666666666666 \cdot \left(\sqrt{2} \cdot \sqrt{-\log u1}\right)\right) \cdot 1 + 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
Applied rewrites98.1%
lift-/.f64N/A
metadata-eval98.1
Applied rewrites98.1%
(FPCore (u1 u2) :precision binary64 (fma (sqrt (* (log u1) -2.0)) 0.16666666666666666 0.5))
double code(double u1, double u2) {
return fma(sqrt((log(u1) * -2.0)), 0.16666666666666666, 0.5);
}
function code(u1, u2) return fma(sqrt(Float64(log(u1) * -2.0)), 0.16666666666666666, 0.5) end
code[u1_, u2_] := N[(N[Sqrt[N[(N[Log[u1], $MachinePrecision] * -2.0), $MachinePrecision]], $MachinePrecision] * 0.16666666666666666 + 0.5), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\sqrt{\log u1 \cdot -2}, 0.16666666666666666, 0.5\right)
\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 rewrites98.0%
herbie shell --seed 2024318
(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))