
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI))))))
(t_1 (sin t_0))
(t_2 (cos t_0)))
(/
1.0
(sqrt
(+
1.0
(/
(*
(/
1.0
(+
(/ (* t_2 t_2) (* alphax alphax))
(/ (* t_1 t_1) (* alphay alphay))))
u0)
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = atanf(((alphay / alphax) * tanf((((2.0f * ((float) M_PI)) * u1) + (0.5f * ((float) M_PI))))));
float t_1 = sinf(t_0);
float t_2 = cosf(t_0);
return 1.0f / sqrtf((1.0f + (((1.0f / (((t_2 * t_2) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = atan(Float32(Float32(alphay / alphax) * tan(Float32(Float32(Float32(Float32(2.0) * Float32(pi)) * u1) + Float32(Float32(0.5) * Float32(pi)))))) t_1 = sin(t_0) t_2 = cos(t_0) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(Float32(Float32(1.0) / Float32(Float32(Float32(t_2 * t_2) / Float32(alphax * alphax)) + Float32(Float32(t_1 * t_1) / Float32(alphay * alphay)))) * u0) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = atan(((alphay / alphax) * tan((((single(2.0) * single(pi)) * u1) + (single(0.5) * single(pi)))))); t_1 = sin(t_0); t_2 = cos(t_0); tmp = single(1.0) / sqrt((single(1.0) + (((single(1.0) / (((t_2 * t_2) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(\left(2 \cdot \pi\right) \cdot u1 + 0.5 \cdot \pi\right)\right)\\
t_1 := \sin t\_0\\
t_2 := \cos t\_0\\
\frac{1}{\sqrt{1 + \frac{\frac{1}{\frac{t\_2 \cdot t\_2}{alphax \cdot alphax} + \frac{t\_1 \cdot t\_1}{alphay \cdot alphay}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI))))))
(t_1 (sin t_0))
(t_2 (cos t_0)))
(/
1.0
(sqrt
(+
1.0
(/
(*
(/
1.0
(+
(/ (* t_2 t_2) (* alphax alphax))
(/ (* t_1 t_1) (* alphay alphay))))
u0)
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = atanf(((alphay / alphax) * tanf((((2.0f * ((float) M_PI)) * u1) + (0.5f * ((float) M_PI))))));
float t_1 = sinf(t_0);
float t_2 = cosf(t_0);
return 1.0f / sqrtf((1.0f + (((1.0f / (((t_2 * t_2) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = atan(Float32(Float32(alphay / alphax) * tan(Float32(Float32(Float32(Float32(2.0) * Float32(pi)) * u1) + Float32(Float32(0.5) * Float32(pi)))))) t_1 = sin(t_0) t_2 = cos(t_0) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(Float32(Float32(1.0) / Float32(Float32(Float32(t_2 * t_2) / Float32(alphax * alphax)) + Float32(Float32(t_1 * t_1) / Float32(alphay * alphay)))) * u0) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = atan(((alphay / alphax) * tan((((single(2.0) * single(pi)) * u1) + (single(0.5) * single(pi)))))); t_1 = sin(t_0); t_2 = cos(t_0); tmp = single(1.0) / sqrt((single(1.0) + (((single(1.0) / (((t_2 * t_2) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(\left(2 \cdot \pi\right) \cdot u1 + 0.5 \cdot \pi\right)\right)\\
t_1 := \sin t\_0\\
t_2 := \cos t\_0\\
\frac{1}{\sqrt{1 + \frac{\frac{1}{\frac{t\_2 \cdot t\_2}{alphax \cdot alphax} + \frac{t\_1 \cdot t\_1}{alphay \cdot alphay}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (atan (* alphay (/ (tan (* PI (+ 0.5 (* 2.0 u1)))) alphax)))))
(/
1.0
(sqrt
(+
1.0
(/
(* (pow (hypot (/ (sin t_0) alphay) (/ (cos t_0) alphax)) -2.0) u0)
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = atanf((alphay * (tanf((((float) M_PI) * (0.5f + (2.0f * u1)))) / alphax)));
return 1.0f / sqrtf((1.0f + ((powf(hypotf((sinf(t_0) / alphay), (cosf(t_0) / alphax)), -2.0f) * u0) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = atan(Float32(alphay * Float32(tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) / alphax))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32((hypot(Float32(sin(t_0) / alphay), Float32(cos(t_0) / alphax)) ^ Float32(-2.0)) * u0) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = atan((alphay * (tan((single(pi) * (single(0.5) + (single(2.0) * u1)))) / alphax))); tmp = single(1.0) / sqrt((single(1.0) + (((hypot((sin(t_0) / alphay), (cos(t_0) / alphax)) ^ single(-2.0)) * u0) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(alphay \cdot \frac{\tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right)}{alphax}\right)\\
\frac{1}{\sqrt{1 + \frac{{\left(\mathsf{hypot}\left(\frac{\sin t\_0}{alphay}, \frac{\cos t\_0}{alphax}\right)\right)}^{-2} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
Taylor expanded in u1 around 0 99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(pow
(hypot
(/ (sin (atan (* alphay (/ (tan (* PI 0.5)) alphax)))) alphay)
(/
(cos (atan (* alphay (/ (tan (* PI (+ 0.5 (* 2.0 u1)))) alphax))))
alphax))
-2.0))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * powf(hypotf((sinf(atanf((alphay * (tanf((((float) M_PI) * 0.5f)) / alphax)))) / alphay), (cosf(atanf((alphay * (tanf((((float) M_PI) * (0.5f + (2.0f * u1)))) / alphax)))) / alphax)), -2.0f)) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * (hypot(Float32(sin(atan(Float32(alphay * Float32(tan(Float32(Float32(pi) * Float32(0.5))) / alphax)))) / alphay), Float32(cos(atan(Float32(alphay * Float32(tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) / alphax)))) / alphax)) ^ Float32(-2.0))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0) / sqrt((single(1.0) + ((u0 * (hypot((sin(atan((alphay * (tan((single(pi) * single(0.5))) / alphax)))) / alphay), (cos(atan((alphay * (tan((single(pi) * (single(0.5) + (single(2.0) * u1)))) / alphax)))) / alphax)) ^ single(-2.0))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot {\left(\mathsf{hypot}\left(\frac{\sin \tan^{-1} \left(alphay \cdot \frac{\tan \left(\pi \cdot 0.5\right)}{alphax}\right)}{alphay}, \frac{\cos \tan^{-1} \left(alphay \cdot \frac{\tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right)}{alphax}\right)}{alphax}\right)\right)}^{-2}}{1 - u0}}}
\end{array}
Initial program 99.3%
Taylor expanded in u1 around 0 99.3%
Simplified99.3%
Taylor expanded in u1 around 0 98.1%
*-commutative97.7%
Simplified98.1%
Final simplification98.1%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
(pow alphay 2.0)
(pow (sin (atan (* alphay (/ (tan (* PI 0.5)) alphax)))) 2.0)))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * (powf(alphay, 2.0f) / powf(sinf(atanf((alphay * (tanf((((float) M_PI) * 0.5f)) / alphax)))), 2.0f))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32((alphay ^ Float32(2.0)) / (sin(atan(Float32(alphay * Float32(tan(Float32(Float32(pi) * Float32(0.5))) / alphax)))) ^ Float32(2.0)))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0) / sqrt((single(1.0) + ((u0 * ((alphay ^ single(2.0)) / (sin(atan((alphay * (tan((single(pi) * single(0.5))) / alphax)))) ^ single(2.0)))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{{alphay}^{2}}{{\sin \tan^{-1} \left(alphay \cdot \frac{\tan \left(\pi \cdot 0.5\right)}{alphax}\right)}^{2}}}{1 - u0}}}
\end{array}
Initial program 99.3%
Taylor expanded in alphay around 0 97.7%
associate-/l*97.7%
associate-*r*97.7%
distribute-rgt-out97.7%
Simplified97.7%
Taylor expanded in u1 around 0 97.7%
*-commutative97.7%
Simplified97.7%
Final simplification97.7%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
(pow alphax 2.0)
(/
1.0
(+
1.0
(pow
(* alphay (/ (tan (* (+ (+ 1.0 PI) -1.0) (fma 2.0 u1 0.5))) alphax))
2.0)))))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * (powf(alphax, 2.0f) / (1.0f / (1.0f + powf((alphay * (tanf((((1.0f + ((float) M_PI)) + -1.0f) * fmaf(2.0f, u1, 0.5f))) / alphax)), 2.0f))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32((alphax ^ Float32(2.0)) / Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(alphay * Float32(tan(Float32(Float32(Float32(Float32(1.0) + Float32(pi)) + Float32(-1.0)) * fma(Float32(2.0), u1, Float32(0.5)))) / alphax)) ^ Float32(2.0)))))) / Float32(Float32(1.0) - u0))))) end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{{alphax}^{2}}{\frac{1}{1 + {\left(alphay \cdot \frac{\tan \left(\left(\left(1 + \pi\right) + -1\right) \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right)}{alphax}\right)}^{2}}}}{1 - u0}}}
\end{array}
Initial program 99.3%
Taylor expanded in alphay around inf 49.6%
associate-/l*49.6%
associate-*r*49.6%
distribute-rgt-out49.5%
Simplified49.5%
unpow249.5%
cos-atan47.2%
cos-atan49.0%
frac-times49.0%
metadata-eval49.0%
add-sqr-sqrt49.0%
Applied egg-rr49.0%
associate-*r/49.0%
associate-*l/49.0%
*-commutative49.0%
Simplified49.0%
expm1-log1p-u49.6%
expm1-undefine49.6%
log1p-undefine49.6%
rem-exp-log49.6%
+-commutative49.6%
Applied egg-rr49.6%
Final simplification49.6%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
(pow alphax 2.0)
(/
1.0
(+
1.0
(pow (* alphay (/ (tan (* PI (fma 2.0 u1 0.5))) alphax)) 2.0)))))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * (powf(alphax, 2.0f) / (1.0f / (1.0f + powf((alphay * (tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) / alphax)), 2.0f))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32((alphax ^ Float32(2.0)) / Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(alphay * Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) / alphax)) ^ Float32(2.0)))))) / Float32(Float32(1.0) - u0))))) end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{{alphax}^{2}}{\frac{1}{1 + {\left(alphay \cdot \frac{\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right)}{alphax}\right)}^{2}}}}{1 - u0}}}
\end{array}
Initial program 99.3%
Taylor expanded in alphay around inf 49.6%
associate-/l*49.6%
associate-*r*49.6%
distribute-rgt-out49.5%
Simplified49.5%
unpow249.5%
cos-atan47.2%
cos-atan49.0%
frac-times49.0%
metadata-eval49.0%
add-sqr-sqrt49.0%
Applied egg-rr49.0%
associate-*r/49.0%
associate-*l/49.0%
*-commutative49.0%
Simplified49.0%
Final simplification49.0%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
(pow alphax 2.0)
(/ 1.0 (+ 1.0 (pow (* (/ 1.0 0.0) (/ alphay alphax)) 2.0)))))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * (powf(alphax, 2.0f) / (1.0f / (1.0f + powf(((1.0f / 0.0f) * (alphay / alphax)), 2.0f))))) / (1.0f - u0))));
}
real(4) function code(u0, u1, alphax, alphay)
real(4), intent (in) :: u0
real(4), intent (in) :: u1
real(4), intent (in) :: alphax
real(4), intent (in) :: alphay
code = 1.0e0 / sqrt((1.0e0 + ((u0 * ((alphax ** 2.0e0) / (1.0e0 / (1.0e0 + (((1.0e0 / 0.0e0) * (alphay / alphax)) ** 2.0e0))))) / (1.0e0 - u0))))
end function
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32((alphax ^ Float32(2.0)) / Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(Float32(Float32(1.0) / Float32(0.0)) * Float32(alphay / alphax)) ^ Float32(2.0)))))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0) / sqrt((single(1.0) + ((u0 * ((alphax ^ single(2.0)) / (single(1.0) / (single(1.0) + (((single(1.0) / single(0.0)) * (alphay / alphax)) ^ single(2.0)))))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{{alphax}^{2}}{\frac{1}{1 + {\left(\frac{1}{0} \cdot \frac{alphay}{alphax}\right)}^{2}}}}{1 - u0}}}
\end{array}
Initial program 99.3%
Taylor expanded in alphay around inf 49.6%
associate-/l*49.6%
associate-*r*49.6%
distribute-rgt-out49.5%
Simplified49.5%
unpow249.5%
cos-atan47.2%
cos-atan49.0%
frac-times49.0%
metadata-eval49.0%
add-sqr-sqrt49.0%
Applied egg-rr49.0%
expm1-log1p-u49.6%
expm1-undefine49.6%
log1p-undefine49.6%
rem-exp-log49.6%
+-commutative49.6%
Applied egg-rr49.6%
Taylor expanded in u1 around 0 20.2%
*-commutative20.2%
metadata-eval20.2%
associate-/l*20.2%
*-rgt-identity20.2%
sin-PI/220.2%
*-commutative20.2%
metadata-eval20.2%
associate-/l*20.2%
*-rgt-identity20.2%
cos-PI/26.3%
Simplified6.3%
Final simplification6.3%
herbie shell --seed 2024053
(FPCore (u0 u1 alphax alphay)
:name "Trowbridge-Reitz Sample, sample surface normal, cosTheta"
:precision binary32
:pre (and (and (and (and (<= 2.328306437e-10 u0) (<= u0 1.0)) (and (<= 2.328306437e-10 u1) (<= u1 0.5))) (and (<= 0.0001 alphax) (<= alphax 1.0))) (and (<= 0.0001 alphay) (<= alphay 1.0)))
(/ 1.0 (sqrt (+ 1.0 (/ (* (/ 1.0 (+ (/ (* (cos (atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI)))))) (cos (atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI))))))) (* alphax alphax)) (/ (* (sin (atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI)))))) (sin (atan (* (/ alphay alphax) (tan (+ (* (* 2.0 PI) u1) (* 0.5 PI))))))) (* alphay alphay)))) u0) (- 1.0 u0))))))