
(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 7 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
(sin
(atan
(* (/ alphay alphax) (tan (+ (* u1 (* PI 2.0)) (* PI 0.5))))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
(/
1.0
(+
(+
(+
1.0
(pow
(/
(cos (atan (* (tan (* PI (fma 2.0 u1 0.5))) (/ alphay alphax))))
alphax)
2.0))
-1.0)
(/ (* t_0 t_0) (* alphay alphay))))
u0)
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = sinf(atanf(((alphay / alphax) * tanf(((u1 * (((float) M_PI) * 2.0f)) + (((float) M_PI) * 0.5f))))));
return 1.0f / sqrtf((1.0f + (((1.0f / (((1.0f + powf((cosf(atanf((tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) * (alphay / alphax)))) / alphax), 2.0f)) + -1.0f) + ((t_0 * t_0) / (alphay * alphay)))) * u0) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = sin(atan(Float32(Float32(alphay / alphax) * tan(Float32(Float32(u1 * Float32(Float32(pi) * Float32(2.0))) + Float32(Float32(pi) * Float32(0.5))))))) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(Float32(Float32(Float32(1.0) / Float32(Float32(Float32(Float32(1.0) + (Float32(cos(atan(Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) * Float32(alphay / alphax)))) / alphax) ^ Float32(2.0))) + Float32(-1.0)) + Float32(Float32(t_0 * t_0) / Float32(alphay * alphay)))) * u0) / Float32(Float32(1.0) - u0))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(u1 \cdot \left(\pi \cdot 2\right) + \pi \cdot 0.5\right)\right)\\
\frac{1}{\sqrt{1 + \frac{\frac{1}{\left(\left(1 + {\left(\frac{\cos \tan^{-1} \left(\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right)}{alphax}\right)}^{2}\right) + -1\right) + \frac{t\_0 \cdot t\_0}{alphay \cdot alphay}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
log1p-undefine99.3%
rem-exp-log99.3%
+-commutative99.3%
div-inv99.3%
div-inv99.3%
div-inv99.3%
clear-num99.3%
Applied egg-rr99.3%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(sin
(atan
(* (/ alphay alphax) (tan (+ (* u1 (* PI 2.0)) (* PI 0.5))))))))
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(/
1.0
(+
(/ (* t_0 t_0) (* alphay alphay))
(/
(/
1.0
(+
1.0
(pow
(/ (tan (+ (* PI 0.5) (* PI (* 2.0 u1)))) (/ alphax alphay))
2.0)))
(* alphax alphax)))))
(- 1.0 u0)))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = sinf(atanf(((alphay / alphax) * tanf(((u1 * (((float) M_PI) * 2.0f)) + (((float) M_PI) * 0.5f))))));
return 1.0f / sqrtf((1.0f + ((u0 * (1.0f / (((t_0 * t_0) / (alphay * alphay)) + ((1.0f / (1.0f + powf((tanf(((((float) M_PI) * 0.5f) + (((float) M_PI) * (2.0f * u1)))) / (alphax / alphay)), 2.0f))) / (alphax * alphax))))) / (1.0f - u0))));
}
function code(u0, u1, alphax, alphay) t_0 = sin(atan(Float32(Float32(alphay / alphax) * tan(Float32(Float32(u1 * Float32(Float32(pi) * Float32(2.0))) + Float32(Float32(pi) * Float32(0.5))))))) 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(tan(Float32(Float32(Float32(pi) * Float32(0.5)) + Float32(Float32(pi) * Float32(Float32(2.0) * u1)))) / Float32(alphax / alphay)) ^ Float32(2.0)))) / Float32(alphax * alphax))))) / Float32(Float32(1.0) - u0))))) end
function tmp = code(u0, u1, alphax, alphay) t_0 = sin(atan(((alphay / alphax) * tan(((u1 * (single(pi) * single(2.0))) + (single(pi) * single(0.5))))))); tmp = single(1.0) / sqrt((single(1.0) + ((u0 * (single(1.0) / (((t_0 * t_0) / (alphay * alphay)) + ((single(1.0) / (single(1.0) + ((tan(((single(pi) * single(0.5)) + (single(pi) * (single(2.0) * u1)))) / (alphax / alphay)) ^ single(2.0)))) / (alphax * alphax))))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(u1 \cdot \left(\pi \cdot 2\right) + \pi \cdot 0.5\right)\right)\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot \frac{1}{\frac{t\_0 \cdot t\_0}{alphay \cdot alphay} + \frac{\frac{1}{1 + {\left(\frac{\tan \left(\pi \cdot 0.5 + \pi \cdot \left(2 \cdot u1\right)\right)}{\frac{alphax}{alphay}}\right)}^{2}}}{alphax \cdot alphax}}}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
fma-undefine99.3%
distribute-rgt-in99.3%
Applied egg-rr99.3%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(pow
(fma
(pow
(/ (sin (atan (* (tan (* PI (fma 2.0 u1 0.5))) (/ alphay alphax)))) alphay)
-2.0)
(/ u0 (- 1.0 u0))
1.0)
-0.5))
float code(float u0, float u1, float alphax, float alphay) {
return powf(fmaf(powf((sinf(atanf((tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) * (alphay / alphax)))) / alphay), -2.0f), (u0 / (1.0f - u0)), 1.0f), -0.5f);
}
function code(u0, u1, alphax, alphay) return fma((Float32(sin(atan(Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) * Float32(alphay / alphax)))) / alphay) ^ Float32(-2.0)), Float32(u0 / Float32(Float32(1.0) - u0)), Float32(1.0)) ^ Float32(-0.5) end
\begin{array}{l}
\\
{\left(\mathsf{fma}\left({\left(\frac{\sin \tan^{-1} \left(\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right)}{alphay}\right)}^{-2}, \frac{u0}{1 - u0}, 1\right)\right)}^{-0.5}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
Taylor expanded in alphax around inf 98.0%
add-log-exp98.0%
metadata-eval98.0%
+-lft-identity98.0%
Applied egg-rr98.0%
pow1/298.0%
pow-flip98.5%
Applied egg-rr98.5%
Final simplification98.5%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(sqrt
(/
1.0
(+
1.0
(/
(* u0 (pow alphay 2.0))
(*
(- 1.0 u0)
(pow
(sin (atan (/ (* alphay (tan (* PI (- 0.5 (* u1 -2.0))))) alphax)))
2.0)))))))
float code(float u0, float u1, float alphax, float alphay) {
return sqrtf((1.0f / (1.0f + ((u0 * powf(alphay, 2.0f)) / ((1.0f - u0) * powf(sinf(atanf(((alphay * tanf((((float) M_PI) * (0.5f - (u1 * -2.0f))))) / alphax))), 2.0f))))));
}
function code(u0, u1, alphax, alphay) return sqrt(Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(u0 * (alphay ^ Float32(2.0))) / Float32(Float32(Float32(1.0) - u0) * (sin(atan(Float32(Float32(alphay * tan(Float32(Float32(pi) * Float32(Float32(0.5) - Float32(u1 * Float32(-2.0)))))) / alphax))) ^ Float32(2.0))))))) end
function tmp = code(u0, u1, alphax, alphay) tmp = sqrt((single(1.0) / (single(1.0) + ((u0 * (alphay ^ single(2.0))) / ((single(1.0) - u0) * (sin(atan(((alphay * tan((single(pi) * (single(0.5) - (u1 * single(-2.0)))))) / alphax))) ^ single(2.0))))))); end
\begin{array}{l}
\\
\sqrt{\frac{1}{1 + \frac{u0 \cdot {alphay}^{2}}{\left(1 - u0\right) \cdot {\sin \tan^{-1} \left(\frac{alphay \cdot \tan \left(\pi \cdot \left(0.5 - u1 \cdot -2\right)\right)}{alphax}\right)}^{2}}}}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
Taylor expanded in alphax around inf 98.0%
add-log-exp98.0%
metadata-eval98.0%
+-lft-identity98.0%
Applied egg-rr98.0%
Taylor expanded in u1 around -inf 98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
1.0
(/
(*
u0
(pow
(/
(sin (atan (/ (* alphay (tan (* PI (- 0.5 (* u1 -2.0))))) alphax)))
alphay)
-2.0))
(- 1.0 u0))))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf((1.0f + ((u0 * powf((sinf(atanf(((alphay * tanf((((float) M_PI) * (0.5f - (u1 * -2.0f))))) / alphax))) / alphay), -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(sin(atan(Float32(Float32(alphay * tan(Float32(Float32(pi) * Float32(Float32(0.5) - Float32(u1 * Float32(-2.0)))))) / alphax))) / alphay) ^ 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 * ((sin(atan(((alphay * tan((single(pi) * (single(0.5) - (u1 * single(-2.0)))))) / alphax))) / alphay) ^ single(-2.0))) / (single(1.0) - u0)))); end
\begin{array}{l}
\\
\frac{1}{\sqrt{1 + \frac{u0 \cdot {\left(\frac{\sin \tan^{-1} \left(\frac{alphay \cdot \tan \left(\pi \cdot \left(0.5 - u1 \cdot -2\right)\right)}{alphax}\right)}{alphay}\right)}^{-2}}{1 - u0}}}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
Taylor expanded in alphax around inf 98.0%
inv-pow98.0%
metadata-eval98.0%
+-lft-identity98.0%
times-frac98.0%
Applied egg-rr98.0%
pow-sqr98.0%
metadata-eval98.0%
Simplified98.0%
Taylor expanded in u1 around -inf 98.0%
Final simplification98.0%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(+
1.0
(*
-0.5
(/
(* u0 (pow alphay 2.0))
(pow
(sin (atan (/ (* alphay (tan (* PI (+ 0.5 (* 2.0 u1))))) alphax)))
2.0)))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f + (-0.5f * ((u0 * powf(alphay, 2.0f)) / powf(sinf(atanf(((alphay * tanf((((float) M_PI) * (0.5f + (2.0f * u1))))) / alphax))), 2.0f)));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) + Float32(Float32(-0.5) * Float32(Float32(u0 * (alphay ^ Float32(2.0))) / (sin(atan(Float32(Float32(alphay * tan(Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(2.0) * u1))))) / alphax))) ^ Float32(2.0))))) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0) + (single(-0.5) * ((u0 * (alphay ^ single(2.0))) / (sin(atan(((alphay * tan((single(pi) * (single(0.5) + (single(2.0) * u1))))) / alphax))) ^ single(2.0)))); end
\begin{array}{l}
\\
1 + -0.5 \cdot \frac{u0 \cdot {alphay}^{2}}{{\sin \tan^{-1} \left(\frac{alphay \cdot \tan \left(\pi \cdot \left(0.5 + 2 \cdot u1\right)\right)}{alphax}\right)}^{2}}
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
Taylor expanded in alphax around inf 98.0%
add-log-exp98.0%
metadata-eval98.0%
+-lft-identity98.0%
Applied egg-rr98.0%
Taylor expanded in u0 around 0 94.5%
Final simplification94.5%
(FPCore (u0 u1 alphax alphay) :precision binary32 1.0)
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f;
}
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
end function
function code(u0, u1, alphax, alphay) return Float32(1.0) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0); end
\begin{array}{l}
\\
1
\end{array}
Initial program 99.3%
Applied egg-rr99.3%
Taylor expanded in alphax around inf 98.0%
inv-pow98.0%
metadata-eval98.0%
+-lft-identity98.0%
times-frac98.0%
Applied egg-rr98.0%
pow-sqr98.0%
metadata-eval98.0%
Simplified98.0%
Taylor expanded in alphay around 0 90.5%
Final simplification90.5%
herbie shell --seed 2024110
(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))))))