
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \cos \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2) :precision binary32 (if (<= (- 1.0 u1) 0.9965000152587891) (* (cos (* u2 (* (PI) 2.0))) (sqrt (- (log (- 1.0 u1))))) (* (cos (* (+ u2 u2) (PI))) (sqrt (- (- (* (* -0.5 u1) u1) u1))))))
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u1 \leq 0.9965000152587891:\\
\;\;\;\;\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;\cos \left(\left(u2 + u2\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \sqrt{-\left(\left(-0.5 \cdot u1\right) \cdot u1 - u1\right)}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u1) < 0.99650002Initial program 94.7%
if 0.99650002 < (-.f32 #s(literal 1 binary32) u1) Initial program 43.7%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3266.3
Applied rewrites67.7%
Applied rewrites97.7%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
count-2-revN/A
distribute-lft-inN/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3297.7
Applied rewrites97.7%
Applied rewrites97.9%
Final simplification97.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))))
(if (<= (* (cos (* u2 (* (PI) 2.0))) t_0) 0.12200000137090683)
(* (cos (* (+ u2 u2) (PI))) (sqrt (- (- (* (* -0.5 u1) u1) u1))))
(* 1.0 t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{if}\;\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot t\_0 \leq 0.12200000137090683:\\
\;\;\;\;\cos \left(\left(u2 + u2\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \sqrt{-\left(\left(-0.5 \cdot u1\right) \cdot u1 - u1\right)}\\
\mathbf{else}:\\
\;\;\;\;1 \cdot t\_0\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.122000001Initial program 48.1%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3264.3
Applied rewrites63.7%
Applied rewrites95.7%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
count-2-revN/A
distribute-lft-inN/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3295.7
Applied rewrites95.7%
Applied rewrites95.9%
if 0.122000001 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 96.7%
Taylor expanded in u2 around 0
Applied rewrites77.8%
Final simplification93.0%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))))
(if (<= (* (cos (* u2 (* (PI) 2.0))) t_0) 0.12200000137090683)
(* (sqrt (- (* (- -1.0 (* 0.5 u1)) u1))) (cos (* (+ u2 u2) (PI))))
(* 1.0 t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{if}\;\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot t\_0 \leq 0.12200000137090683:\\
\;\;\;\;\sqrt{-\left(-1 - 0.5 \cdot u1\right) \cdot u1} \cdot \cos \left(\left(u2 + u2\right) \cdot \mathsf{PI}\left(\right)\right)\\
\mathbf{else}:\\
\;\;\;\;1 \cdot t\_0\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.122000001Initial program 48.1%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3264.3
Applied rewrites64.1%
Applied rewrites95.7%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
count-2-revN/A
distribute-lft-inN/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3295.7
Applied rewrites95.7%
if 0.122000001 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 96.7%
Taylor expanded in u2 around 0
Applied rewrites77.8%
Final simplification92.9%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))))
(if (<= (* (cos (* u2 (* (PI) 2.0))) t_0) 0.012000000104308128)
(* (sqrt (- (- u1))) (cos (* (+ u2 u2) (PI))))
(* 1.0 t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{if}\;\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot t\_0 \leq 0.012000000104308128:\\
\;\;\;\;\sqrt{-\left(-u1\right)} \cdot \cos \left(\left(u2 + u2\right) \cdot \mathsf{PI}\left(\right)\right)\\
\mathbf{else}:\\
\;\;\;\;1 \cdot t\_0\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0120000001Initial program 37.0%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3266.4
Applied rewrites66.3%
Applied rewrites97.6%
lift-*.f32N/A
*-commutativeN/A
lift-*.f32N/A
count-2-revN/A
distribute-lft-inN/A
distribute-rgt-outN/A
lower-*.f32N/A
lower-+.f3297.6
Applied rewrites97.6%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3292.2
Applied rewrites92.2%
if 0.0120000001 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 88.3%
Taylor expanded in u2 around 0
Applied rewrites75.3%
Final simplification86.0%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sqrt (- (log (- 1.0 u1))))))
(if (<= (* (cos (* u2 (* (PI) 2.0))) t_0) 0.05550000071525574)
(* (sqrt (- (* (- -1.0 (* 0.5 u1)) u1))) 1.0)
(* 1.0 t_0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{-\log \left(1 - u1\right)}\\
\mathbf{if}\;\cos \left(u2 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot t\_0 \leq 0.05550000071525574:\\
\;\;\;\;\sqrt{-\left(-1 - 0.5 \cdot u1\right) \cdot u1} \cdot 1\\
\mathbf{else}:\\
\;\;\;\;1 \cdot t\_0\\
\end{array}
\end{array}
if (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) < 0.0555000007Initial program 44.3%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3266.4
Applied rewrites65.0%
Applied rewrites97.1%
Taylor expanded in u2 around 0
Applied rewrites77.4%
if 0.0555000007 < (*.f32 (sqrt.f32 (neg.f32 (log.f32 (-.f32 #s(literal 1 binary32) u1)))) (cos.f32 (*.f32 (*.f32 #s(literal 2 binary32) (PI.f32)) u2))) Initial program 94.4%
Taylor expanded in u2 around 0
Applied rewrites76.5%
Final simplification77.2%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (* (- -1.0 (* 0.5 u1)) u1))) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-((-1.0f - (0.5f * u1)) * u1)) * 1.0f;
}
real(4) function code(costheta_i, u1, u2)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: u1
real(4), intent (in) :: u2
code = sqrt(-(((-1.0e0) - (0.5e0 * u1)) * u1)) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-Float32(Float32(Float32(-1.0) - Float32(Float32(0.5) * u1)) * u1))) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-((single(-1.0) - (single(0.5) * u1)) * u1)) * single(1.0); end
\begin{array}{l}
\\
\sqrt{-\left(-1 - 0.5 \cdot u1\right) \cdot u1} \cdot 1
\end{array}
Initial program 55.8%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3259.8
Applied rewrites60.2%
Applied rewrites88.5%
Taylor expanded in u2 around 0
Applied rewrites72.0%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (- u1))) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-(-u1)) * 1.0f;
}
real(4) function code(costheta_i, u1, u2)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: u1
real(4), intent (in) :: u2
code = sqrt(-(-u1)) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-Float32(-u1))) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-(-u1)) * single(1.0); end
\begin{array}{l}
\\
\sqrt{-\left(-u1\right)} \cdot 1
\end{array}
Initial program 55.8%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3277.7
Applied rewrites77.7%
Taylor expanded in u2 around 0
Applied rewrites64.6%
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- u1)) 1.0))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-u1) * 1.0f;
}
real(4) function code(costheta_i, u1, u2)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: u1
real(4), intent (in) :: u2
code = sqrt(-u1) * 1.0e0
end function
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-u1)) * Float32(1.0)) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-u1) * single(1.0); end
\begin{array}{l}
\\
\sqrt{-u1} \cdot 1
\end{array}
Initial program 55.8%
Taylor expanded in u1 around 0
mul-1-negN/A
lower-neg.f3277.7
Applied rewrites77.7%
Taylor expanded in u2 around 0
Applied rewrites64.6%
Applied rewrites-0.0%
herbie shell --seed 2024312
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_x"
:precision binary32
:pre (and (and (and (> cosTheta_i 0.9999) (<= cosTheta_i 1.0)) (and (<= 2.328306437e-10 u1) (<= u1 1.0))) (and (<= 2.328306437e-10 u2) (<= u2 1.0)))
(* (sqrt (- (log (- 1.0 u1)))) (cos (* (* 2.0 (PI)) u2))))