
(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 4 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 (tan (* PI (+ 0.5 (* 2.0 u1)))))
(t_1 (sin (atan (* t_0 (/ alphay alphax))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
(/
1.0
(+
(/
(/ 1.0 (+ 1.0 (pow (* alphay (/ t_0 alphax)) 2.0)))
(* 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 = tanf((((float) M_PI) * (0.5f + (2.0f * u1))));
float t_1 = sinf(atanf((t_0 * (alphay / alphax))));
return 1.0f / sqrtf((1.0f + (((1.0f / (((1.0f / (1.0f + powf((alphay * (t_0 / alphax)), 2.0f))) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) t_1 = sin(atan(Float32(t_0 * Float32(alphay / alphax)))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(Float32(Float32(1.0) / Float32(Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(alphay * Float32(t_0 / alphax)) ^ Float32(2.0)))) / 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 = tan((single(pi) * (single(0.5) + (single(2.0) * u1)))); t_1 = sin(atan((t_0 * (alphay / alphax)))); tmp = single(1.0) / sqrt((single(1.0) + (((single(1.0) / (((single(1.0) / (single(1.0) + ((alphay * (t_0 / alphax)) ^ single(2.0)))) / (alphax * alphax)) + ((t_1 * t_1) / (alphay * alphay)))) * u0) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right)\\
t_1 := \sin \tan^{-1} \left(t\_0 \cdot \frac{alphay}{alphax}\right)\\
\frac{1}{\sqrt{1 + \frac{\frac{1}{\frac{\frac{1}{1 + {\left(alphay \cdot \frac{t\_0}{alphax}\right)}^{2}}}{alphax \cdot alphax} + \frac{t\_1 \cdot t\_1}{alphay \cdot alphay}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
cos-atan99.3%
cos-atan99.3%
frac-times99.3%
metadata-eval99.3%
Applied egg-rr99.3%
associate-/r/99.3%
*-commutative99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (tan (* PI (+ 0.5 (* 2.0 u1))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
1.0
(+
(/
(/ 1.0 (+ 1.0 (pow (* alphay (/ t_0 alphax)) 2.0)))
(* alphax alphax))
(/
(*
(sin (atan (* t_0 (/ alphay alphax))))
(sin (atan (* (/ alphay alphax) (tan (* PI 0.5))))))
(* alphay alphay)))))
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = tanf((((float) M_PI) * (0.5f + (2.0f * u1))));
return 1.0f / sqrtf((1.0f + ((u0 * (1.0f / (((1.0f / (1.0f + powf((alphay * (t_0 / alphax)), 2.0f))) / (alphax * alphax)) + ((sinf(atanf((t_0 * (alphay / alphax)))) * sinf(atanf(((alphay / alphax) * tanf((((float) M_PI) * 0.5f)))))) / (alphay * alphay))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32(Float32(1.0) / Float32(Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(alphay * Float32(t_0 / alphax)) ^ Float32(2.0)))) / Float32(alphax * alphax)) + Float32(Float32(sin(atan(Float32(t_0 * Float32(alphay / alphax)))) * sin(atan(Float32(Float32(alphay / alphax) * tan(Float32(Float32(pi) * Float32(0.5))))))) / Float32(alphay * alphay))))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = tan((single(pi) * (single(0.5) + (single(2.0) * u1)))); tmp = single(1.0) / sqrt((single(1.0) + ((u0 * (single(1.0) / (((single(1.0) / (single(1.0) + ((alphay * (t_0 / alphax)) ^ single(2.0)))) / (alphax * alphax)) + ((sin(atan((t_0 * (alphay / alphax)))) * sin(atan(((alphay / alphax) * tan((single(pi) * single(0.5))))))) / (alphay * alphay))))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right)\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{1}{\frac{\frac{1}{1 + {\left(alphay \cdot \frac{t\_0}{alphax}\right)}^{2}}}{alphax \cdot alphax} + \frac{\sin \tan^{-1} \left(t\_0 \cdot \frac{alphay}{alphax}\right) \cdot \sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(\pi \cdot 0.5\right)\right)}{alphay \cdot alphay}}}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
cos-atan99.3%
cos-atan99.3%
frac-times99.3%
metadata-eval99.3%
Applied egg-rr99.3%
associate-/r/99.3%
*-commutative99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
Taylor expanded in u1 around 0 98.4%
*-commutative98.4%
Simplified98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(sin (atan (* (tan (* PI (+ 0.5 (* 2.0 u1)))) (/ alphay alphax))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
1.0
(+
(/ (* t_0 t_0) (* alphay alphay))
(/
(/ 1.0 (+ 1.0 (pow (* alphay (/ (tan (* PI 0.5)) alphax)) 2.0)))
(* alphax alphax)))))
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = sinf(atanf((tanf((((float) M_PI) * (0.5f + (2.0f * u1)))) * (alphay / alphax))));
return 1.0f / sqrtf((1.0f + ((u0 * (1.0f / (((t_0 * t_0) / (alphay * alphay)) + ((1.0f / (1.0f + powf((alphay * (tanf((((float) M_PI) * 0.5f)) / alphax)), 2.0f))) / (alphax * alphax))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = sin(atan(Float32(tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) * Float32(alphay / alphax)))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32(Float32(1.0) / Float32(Float32(Float32(t_0 * t_0) / Float32(alphay * alphay)) + Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(alphay * Float32(tan(Float32(Float32(pi) * Float32(0.5))) / alphax)) ^ Float32(2.0)))) / Float32(alphax * alphax))))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = sin(atan((tan((single(pi) * (single(0.5) + (single(2.0) * u1)))) * (alphay / alphax)))); tmp = single(1.0) / sqrt((single(1.0) + ((u0 * (single(1.0) / (((t_0 * t_0) / (alphay * alphay)) + ((single(1.0) / (single(1.0) + ((alphay * (tan((single(pi) * single(0.5))) / alphax)) ^ single(2.0)))) / (alphax * alphax))))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \tan^{-1} \left(\tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right) \cdot \frac{alphay}{alphax}\right)\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{1}{\frac{t\_0 \cdot t\_0}{alphay \cdot alphay} + \frac{\frac{1}{1 + {\left(alphay \cdot \frac{\tan \left(\pi \cdot 0.5\right)}{alphax}\right)}^{2}}}{alphax \cdot alphax}}}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
cos-atan99.3%
cos-atan99.3%
frac-times99.3%
metadata-eval99.3%
Applied egg-rr99.3%
associate-/r/99.3%
*-commutative99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
Taylor expanded in u1 around 0 97.8%
*-commutative98.4%
Simplified97.8%
Final simplification97.8%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(sin (atan (* (tan (* PI (+ 0.5 (* 2.0 u1)))) (/ alphay alphax))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/ 1.0 (+ (/ (* t_0 t_0) (* alphay alphay)) (/ 1.0 (pow alphax 2.0)))))
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = sinf(atanf((tanf((((float) M_PI) * (0.5f + (2.0f * u1)))) * (alphay / alphax))));
return 1.0f / sqrtf((1.0f + ((u0 * (1.0f / (((t_0 * t_0) / (alphay * alphay)) + (1.0f / powf(alphax, 2.0f))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = sin(atan(Float32(tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1)))) * Float32(alphay / alphax)))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(u0 * Float32(Float32(1.0) / Float32(Float32(Float32(t_0 * t_0) / Float32(alphay * alphay)) + Float32(Float32(1.0) / (alphax ^ Float32(2.0)))))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = sin(atan((tan((single(pi) * (single(0.5) + (single(2.0) * u1)))) * (alphay / alphax)))); tmp = single(1.0) / sqrt((single(1.0) + ((u0 * (single(1.0) / (((t_0 * t_0) / (alphay * alphay)) + (single(1.0) / (alphax ^ single(2.0)))))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \tan^{-1} \left(\tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right) \cdot \frac{alphay}{alphax}\right)\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{1}{\frac{t\_0 \cdot t\_0}{alphay \cdot alphay} + \frac{1}{{alphax}^{2}}}}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
cos-atan99.3%
cos-atan99.3%
frac-times99.3%
metadata-eval99.3%
Applied egg-rr99.3%
associate-/r/99.3%
*-commutative99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
*-un-lft-identity99.3%
*-commutative99.3%
associate-*l*99.3%
fma-define99.3%
*-commutative99.3%
Applied egg-rr99.3%
*-rgt-identity99.3%
fma-undefine99.3%
*-commutative99.3%
*-commutative99.3%
+-commutative99.3%
associate-*r*99.3%
distribute-rgt-out99.3%
Simplified99.3%
Taylor expanded in alphay around 0 91.2%
Final simplification91.2%
herbie shell --seed 2024149
(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))))))