
(FPCore (ux uy maxCos) :precision binary32 (let* ((t_0 (+ (- 1.0 ux) (* ux maxCos)))) (* (cos (* (* uy 2.0) PI)) (sqrt (- 1.0 (* t_0 t_0))))))
float code(float ux, float uy, float maxCos) {
float t_0 = (1.0f - ux) + (ux * maxCos);
return cosf(((uy * 2.0f) * ((float) M_PI))) * sqrtf((1.0f - (t_0 * t_0)));
}
function code(ux, uy, maxCos) t_0 = Float32(Float32(Float32(1.0) - ux) + Float32(ux * maxCos)) return Float32(cos(Float32(Float32(uy * Float32(2.0)) * Float32(pi))) * sqrt(Float32(Float32(1.0) - Float32(t_0 * t_0)))) end
function tmp = code(ux, uy, maxCos) t_0 = (single(1.0) - ux) + (ux * maxCos); tmp = cos(((uy * single(2.0)) * single(pi))) * sqrt((single(1.0) - (t_0 * t_0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(1 - ux\right) + ux \cdot maxCos\\
\cos \left(\left(uy \cdot 2\right) \cdot \pi\right) \cdot \sqrt{1 - t\_0 \cdot t\_0}
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 19 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (ux uy maxCos) :precision binary32 (let* ((t_0 (+ (- 1.0 ux) (* ux maxCos)))) (* (cos (* (* uy 2.0) PI)) (sqrt (- 1.0 (* t_0 t_0))))))
float code(float ux, float uy, float maxCos) {
float t_0 = (1.0f - ux) + (ux * maxCos);
return cosf(((uy * 2.0f) * ((float) M_PI))) * sqrtf((1.0f - (t_0 * t_0)));
}
function code(ux, uy, maxCos) t_0 = Float32(Float32(Float32(1.0) - ux) + Float32(ux * maxCos)) return Float32(cos(Float32(Float32(uy * Float32(2.0)) * Float32(pi))) * sqrt(Float32(Float32(1.0) - Float32(t_0 * t_0)))) end
function tmp = code(ux, uy, maxCos) t_0 = (single(1.0) - ux) + (ux * maxCos); tmp = cos(((uy * single(2.0)) * single(pi))) * sqrt((single(1.0) - (t_0 * t_0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(1 - ux\right) + ux \cdot maxCos\\
\cos \left(\left(uy \cdot 2\right) \cdot \pi\right) \cdot \sqrt{1 - t\_0 \cdot t\_0}
\end{array}
\end{array}
(FPCore (ux uy maxCos)
:precision binary32
(*
(cos (* (* uy 2.0) PI))
(sqrt
(fma
(fma (- 1.0 maxCos) (fma ux maxCos (- ux)) (* maxCos -2.0))
ux
(* 2.0 ux)))))
float code(float ux, float uy, float maxCos) {
return cosf(((uy * 2.0f) * ((float) M_PI))) * sqrtf(fmaf(fmaf((1.0f - maxCos), fmaf(ux, maxCos, -ux), (maxCos * -2.0f)), ux, (2.0f * ux)));
}
function code(ux, uy, maxCos) return Float32(cos(Float32(Float32(uy * Float32(2.0)) * Float32(pi))) * sqrt(fma(fma(Float32(Float32(1.0) - maxCos), fma(ux, maxCos, Float32(-ux)), Float32(maxCos * Float32(-2.0))), ux, Float32(Float32(2.0) * ux)))) end
\begin{array}{l}
\\
\cos \left(\left(uy \cdot 2\right) \cdot \pi\right) \cdot \sqrt{\mathsf{fma}\left(\mathsf{fma}\left(1 - maxCos, \mathsf{fma}\left(ux, maxCos, -ux\right), maxCos \cdot -2\right), ux, 2 \cdot ux\right)}
\end{array}
Initial program 60.9%
Taylor expanded in ux around 0
lower-*.f32N/A
cancel-sign-sub-invN/A
metadata-evalN/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
+-commutativeN/A
mul-1-negN/A
*-commutativeN/A
unpow2N/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-neg-inN/A
neg-sub0N/A
associate-+l-N/A
neg-sub0N/A
mul-1-negN/A
+-commutativeN/A
Applied rewrites98.9%
Applied rewrites99.0%
(FPCore (ux uy maxCos)
:precision binary32
(let* ((t_0 (cos (* (* uy 2.0) PI))))
(if (<= t_0 0.999750018119812)
(* t_0 (sqrt (* ux (* ux (+ (/ 2.0 ux) -1.0)))))
(*
(sqrt
(*
ux
(fma maxCos -2.0 (fma (- 1.0 maxCos) (fma ux maxCos (- ux)) 2.0))))
(fma (* -2.0 (* uy uy)) (* PI PI) 1.0)))))
float code(float ux, float uy, float maxCos) {
float t_0 = cosf(((uy * 2.0f) * ((float) M_PI)));
float tmp;
if (t_0 <= 0.999750018119812f) {
tmp = t_0 * sqrtf((ux * (ux * ((2.0f / ux) + -1.0f))));
} else {
tmp = sqrtf((ux * fmaf(maxCos, -2.0f, fmaf((1.0f - maxCos), fmaf(ux, maxCos, -ux), 2.0f)))) * fmaf((-2.0f * (uy * uy)), (((float) M_PI) * ((float) M_PI)), 1.0f);
}
return tmp;
}
function code(ux, uy, maxCos) t_0 = cos(Float32(Float32(uy * Float32(2.0)) * Float32(pi))) tmp = Float32(0.0) if (t_0 <= Float32(0.999750018119812)) tmp = Float32(t_0 * sqrt(Float32(ux * Float32(ux * Float32(Float32(Float32(2.0) / ux) + Float32(-1.0)))))); else tmp = Float32(sqrt(Float32(ux * fma(maxCos, Float32(-2.0), fma(Float32(Float32(1.0) - maxCos), fma(ux, maxCos, Float32(-ux)), Float32(2.0))))) * fma(Float32(Float32(-2.0) * Float32(uy * uy)), Float32(Float32(pi) * Float32(pi)), Float32(1.0))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(uy \cdot 2\right) \cdot \pi\right)\\
\mathbf{if}\;t\_0 \leq 0.999750018119812:\\
\;\;\;\;t\_0 \cdot \sqrt{ux \cdot \left(ux \cdot \left(\frac{2}{ux} + -1\right)\right)}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{ux \cdot \mathsf{fma}\left(maxCos, -2, \mathsf{fma}\left(1 - maxCos, \mathsf{fma}\left(ux, maxCos, -ux\right), 2\right)\right)} \cdot \mathsf{fma}\left(-2 \cdot \left(uy \cdot uy\right), \pi \cdot \pi, 1\right)\\
\end{array}
\end{array}
if (cos.f32 (*.f32 (*.f32 uy #s(literal 2 binary32)) (PI.f32))) < 0.999750018Initial program 58.9%
Taylor expanded in maxCos around 0
sub-negN/A
+-commutativeN/A
unpow2N/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f32N/A
lower--.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower--.f3256.7
Applied rewrites56.7%
Taylor expanded in ux around 0
Applied rewrites91.8%
Taylor expanded in ux around inf
Applied rewrites91.8%
if 0.999750018 < (cos.f32 (*.f32 (*.f32 uy #s(literal 2 binary32)) (PI.f32))) Initial program 57.4%
Taylor expanded in ux around 0
lower-*.f32N/A
cancel-sign-sub-invN/A
metadata-evalN/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
+-commutativeN/A
mul-1-negN/A
*-commutativeN/A
unpow2N/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-neg-inN/A
neg-sub0N/A
associate-+l-N/A
neg-sub0N/A
mul-1-negN/A
+-commutativeN/A
Applied rewrites99.4%
Taylor expanded in uy around 0
+-commutativeN/A
associate-*r*N/A
lower-fma.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f3299.4
Applied rewrites99.4%
Final simplification97.4%
herbie shell --seed 2024230
(FPCore (ux uy maxCos)
:name "UniformSampleCone, x"
:precision binary32
:pre (and (and (and (<= 2.328306437e-10 ux) (<= ux 1.0)) (and (<= 2.328306437e-10 uy) (<= uy 1.0))) (and (<= 0.0 maxCos) (<= maxCos 1.0)))
(* (cos (* (* uy 2.0) PI)) (sqrt (- 1.0 (* (+ (- 1.0 ux) (* ux maxCos)) (+ (- 1.0 ux) (* ux maxCos)))))))