
(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 8 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 (fma 2.0 u1 0.5)))))
(sqrt
(/
1.0
(+
1.0
(/
u0
(*
(+
(/
(/ 1.0 (+ 1.0 (pow (* t_0 (/ alphay alphax)) 2.0)))
(* alphax alphax))
(/
(pow (sin (atan (/ (* t_0 alphay) alphax))) 2.0)
(* alphay alphay)))
(- 1.0 u0))))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f)));
return sqrtf((1.0f / (1.0f + (u0 / ((((1.0f / (1.0f + powf((t_0 * (alphay / alphax)), 2.0f))) / (alphax * alphax)) + (powf(sinf(atanf(((t_0 * alphay) / alphax))), 2.0f) / (alphay * alphay))) * (1.0f - u0))))));
}
function code(u0, u1, alphax, alphay) t_0 = tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) return sqrt(Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(u0 / Float32(Float32(Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + (Float32(t_0 * Float32(alphay / alphax)) ^ Float32(2.0)))) / Float32(alphax * alphax)) + Float32((sin(atan(Float32(Float32(t_0 * alphay) / alphax))) ^ Float32(2.0)) / Float32(alphay * alphay))) * Float32(Float32(1.0) - u0)))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right)\\
\sqrt{\frac{1}{1 + \frac{u0}{\left(\frac{\frac{1}{1 + {\left(t\_0 \cdot \frac{alphay}{alphax}\right)}^{2}}}{alphax \cdot alphax} + \frac{{\sin \tan^{-1} \left(\frac{t\_0 \cdot alphay}{alphax}\right)}^{2}}{alphay \cdot alphay}\right) \cdot \left(1 - u0\right)}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
Applied rewrites99.4%
Taylor expanded in u1 around 0
Applied rewrites99.9%
lift-PI.f32N/A
lift-fma.f32N/A
lift-*.f32N/A
lift-tan.f32N/A
lift-*.f32N/A
lift-/.f32N/A
cos-atanN/A
inv-powN/A
pow-powN/A
Applied rewrites99.9%
Final simplification99.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (pow (* (tan (* PI (fma 2.0 u1 0.5))) (/ alphay alphax)) 2.0)))
(exp
(*
(log1p
(/
u0
(*
(- 1.0 u0)
(+
(/ (+ 1.0 (/ 1.0 (- -1.0 t_0))) (* alphay alphay))
(/ 1.0 (* alphax (* alphax (+ 1.0 t_0))))))))
-0.5))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = powf((tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) * (alphay / alphax)), 2.0f);
return expf((log1pf((u0 / ((1.0f - u0) * (((1.0f + (1.0f / (-1.0f - t_0))) / (alphay * alphay)) + (1.0f / (alphax * (alphax * (1.0f + t_0)))))))) * -0.5f));
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) * Float32(alphay / alphax)) ^ Float32(2.0) return exp(Float32(log1p(Float32(u0 / Float32(Float32(Float32(1.0) - u0) * Float32(Float32(Float32(Float32(1.0) + Float32(Float32(1.0) / Float32(Float32(-1.0) - t_0))) / Float32(alphay * alphay)) + Float32(Float32(1.0) / Float32(alphax * Float32(alphax * Float32(Float32(1.0) + t_0)))))))) * Float32(-0.5))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := {\left(\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right)}^{2}\\
e^{\mathsf{log1p}\left(\frac{u0}{\left(1 - u0\right) \cdot \left(\frac{1 + \frac{1}{-1 - t\_0}}{alphay \cdot alphay} + \frac{1}{alphax \cdot \left(alphax \cdot \left(1 + t\_0\right)\right)}\right)}\right) \cdot -0.5}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
Applied rewrites99.4%
Applied rewrites99.7%
Final simplification99.7%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (pow (* (tan (* PI (fma 2.0 u1 0.5))) (/ alphay alphax)) 2.0)))
(pow
(+
1.0
(/
u0
(*
(- 1.0 u0)
(+
(/ (+ 1.0 (/ 1.0 (- -1.0 t_0))) (* alphay alphay))
(/ 1.0 (* alphax (* alphax (+ 1.0 t_0))))))))
-0.5)))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = powf((tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) * (alphay / alphax)), 2.0f);
return powf((1.0f + (u0 / ((1.0f - u0) * (((1.0f + (1.0f / (-1.0f - t_0))) / (alphay * alphay)) + (1.0f / (alphax * (alphax * (1.0f + t_0)))))))), -0.5f);
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) * Float32(alphay / alphax)) ^ Float32(2.0) return Float32(Float32(1.0) + Float32(u0 / Float32(Float32(Float32(1.0) - u0) * Float32(Float32(Float32(Float32(1.0) + Float32(Float32(1.0) / Float32(Float32(-1.0) - t_0))) / Float32(alphay * alphay)) + Float32(Float32(1.0) / Float32(alphax * Float32(alphax * Float32(Float32(1.0) + t_0)))))))) ^ Float32(-0.5) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := {\left(\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right)}^{2}\\
{\left(1 + \frac{u0}{\left(1 - u0\right) \cdot \left(\frac{1 + \frac{1}{-1 - t\_0}}{alphay \cdot alphay} + \frac{1}{alphax \cdot \left(alphax \cdot \left(1 + t\_0\right)\right)}\right)}\right)}^{-0.5}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
Applied rewrites99.4%
Applied rewrites99.6%
Final simplification99.6%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (pow (* (tan (* PI (fma 2.0 u1 0.5))) (/ alphay alphax)) 2.0)))
(/
1.0
(sqrt
(+
1.0
(/
u0
(*
(- 1.0 u0)
(+
(/ (+ 1.0 (/ 1.0 (- -1.0 t_0))) (* alphay alphay))
(/ 1.0 (* alphax (* alphax (+ 1.0 t_0))))))))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = powf((tanf((((float) M_PI) * fmaf(2.0f, u1, 0.5f))) * (alphay / alphax)), 2.0f);
return 1.0f / sqrtf((1.0f + (u0 / ((1.0f - u0) * (((1.0f + (1.0f / (-1.0f - t_0))) / (alphay * alphay)) + (1.0f / (alphax * (alphax * (1.0f + t_0)))))))));
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(Float32(2.0), u1, Float32(0.5)))) * Float32(alphay / alphax)) ^ Float32(2.0) return Float32(Float32(1.0) / sqrt(Float32(Float32(1.0) + Float32(u0 / Float32(Float32(Float32(1.0) - u0) * Float32(Float32(Float32(Float32(1.0) + Float32(Float32(1.0) / Float32(Float32(-1.0) - t_0))) / Float32(alphay * alphay)) + Float32(Float32(1.0) / Float32(alphax * Float32(alphax * Float32(Float32(1.0) + t_0)))))))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := {\left(\tan \left(\pi \cdot \mathsf{fma}\left(2, u1, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right)}^{2}\\
\frac{1}{\sqrt{1 + \frac{u0}{\left(1 - u0\right) \cdot \left(\frac{1 + \frac{1}{-1 - t\_0}}{alphay \cdot alphay} + \frac{1}{alphax \cdot \left(alphax \cdot \left(1 + t\_0\right)\right)}\right)}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
Applied rewrites99.4%
Applied rewrites99.1%
Final simplification99.1%
(FPCore (u0 u1 alphax alphay) :precision binary32 (sqrt (/ 1.0 (fma (* alphay alphay) (/ u0 (- 1.0 u0)) 1.0))))
float code(float u0, float u1, float alphax, float alphay) {
return sqrtf((1.0f / fmaf((alphay * alphay), (u0 / (1.0f - u0)), 1.0f)));
}
function code(u0, u1, alphax, alphay) return sqrt(Float32(Float32(1.0) / fma(Float32(alphay * alphay), Float32(u0 / Float32(Float32(1.0) - u0)), Float32(1.0)))) end
\begin{array}{l}
\\
\sqrt{\frac{1}{\mathsf{fma}\left(alphay \cdot alphay, \frac{u0}{1 - u0}, 1\right)}}
\end{array}
Initial program 99.4%
Taylor expanded in alphay around 0
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.1%
Applied rewrites97.5%
Taylor expanded in alphax around 0
lower-sqrt.f32N/A
lower-/.f32N/A
+-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-/.f32N/A
lower--.f3297.6
Applied rewrites97.6%
(FPCore (u0 u1 alphax alphay) :precision binary32 (fma -0.5 (/ (* u0 (* alphay alphay)) (- 1.0 u0)) 1.0))
float code(float u0, float u1, float alphax, float alphay) {
return fmaf(-0.5f, ((u0 * (alphay * alphay)) / (1.0f - u0)), 1.0f);
}
function code(u0, u1, alphax, alphay) return fma(Float32(-0.5), Float32(Float32(u0 * Float32(alphay * alphay)) / Float32(Float32(1.0) - u0)), Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \frac{u0 \cdot \left(alphay \cdot alphay\right)}{1 - u0}, 1\right)
\end{array}
Initial program 99.4%
Taylor expanded in alphay around 0
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.1%
Applied rewrites97.5%
Taylor expanded in alphax around 0
lower-sqrt.f32N/A
lower-/.f32N/A
+-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-/.f32N/A
lower--.f3297.6
Applied rewrites97.6%
Taylor expanded in alphay around 0
+-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower--.f3296.2
Applied rewrites96.2%
Final simplification96.2%
(FPCore (u0 u1 alphax alphay) :precision binary32 (fma -0.5 (* u0 (* alphay alphay)) 1.0))
float code(float u0, float u1, float alphax, float alphay) {
return fmaf(-0.5f, (u0 * (alphay * alphay)), 1.0f);
}
function code(u0, u1, alphax, alphay) return fma(Float32(-0.5), Float32(u0 * Float32(alphay * alphay)), Float32(1.0)) end
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, u0 \cdot \left(alphay \cdot alphay\right), 1\right)
\end{array}
Initial program 99.4%
Taylor expanded in alphay around 0
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.1%
Applied rewrites97.5%
Taylor expanded in alphax around 0
lower-sqrt.f32N/A
lower-/.f32N/A
+-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
unpow2N/A
lower-*.f32N/A
lower-/.f32N/A
lower--.f3297.6
Applied rewrites97.6%
Taylor expanded in u0 around 0
associate-*r*N/A
+-commutativeN/A
associate-*r*N/A
lower-fma.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f3294.6
Applied rewrites94.6%
Final simplification94.6%
(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 99.4%
Taylor expanded in u1 around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
Applied rewrites99.4%
Taylor expanded in u0 around 0
Applied rewrites91.7%
herbie shell --seed 2024216
(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))))))