
(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)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u1 + 0.5 \cdot \mathsf{PI}\left(\right)\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)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\frac{alphay}{alphax} \cdot \tan \left(\left(2 \cdot \mathsf{PI}\left(\right)\right) \cdot u1 + 0.5 \cdot \mathsf{PI}\left(\right)\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 (* (PI) (+ 0.5 (* 2.0 u1)))) (t_1 (cos t_0)) (t_2 (sin t_0)))
(sqrt
(/
1.0
(+
1.0
(/
u0
(*
(+
(/
1.0
(*
(* alphax alphax)
(+
1.0
(*
(/ (* alphay alphay) (* alphax alphax))
(/ (pow t_2 2.0) (pow t_1 2.0))))))
(/
(pow (sin (atan (* (/ alphay alphax) (/ t_2 t_1)))) 2.0)
(* alphay alphay)))
(- 1.0 u0))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot \left(0.5 + 2 \cdot u1\right)\\
t_1 := \cos t\_0\\
t_2 := \sin t\_0\\
\sqrt{\frac{1}{1 + \frac{u0}{\left(\frac{1}{\left(alphax \cdot alphax\right) \cdot \left(1 + \frac{alphay \cdot alphay}{alphax \cdot alphax} \cdot \frac{{t\_2}^{2}}{{t\_1}^{2}}\right)} + \frac{{\sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \frac{t\_2}{t\_1}\right)}^{2}}{alphay \cdot alphay}\right) \cdot \left(1 - u0\right)}}}
\end{array}
\end{array}
Initial program 99.3%
lift-*.f32N/A
lift-cos.f32N/A
lift-atan.f32N/A
cos-atanN/A
lift-cos.f32N/A
lift-atan.f32N/A
cos-atanN/A
Applied rewrites92.1%
Taylor expanded in u1 around inf
Applied rewrites99.9%
Taylor expanded in u1 around inf
Applied rewrites99.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* (PI) (+ 0.5 (* 2.0 u1)))) (t_1 (cos t_0)))
(sqrt
(/
1.0
(+
1.0
(/
(/
u0
(+
(/
(/ 1.0 (* alphax alphax))
(+
1.0
(*
(/ (* alphay alphay) (* alphax alphax))
(/
(- 0.5 (* 0.5 (cos (* 2.0 (* (fma 2.0 u1 0.5) (PI))))))
(pow t_1 2.0)))))
(/
(pow (sin (atan (* (/ alphay alphax) (/ (sin t_0) t_1)))) 2.0)
(* alphay alphay))))
(- 1.0 u0)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot \left(0.5 + 2 \cdot u1\right)\\
t_1 := \cos t\_0\\
\sqrt{\frac{1}{1 + \frac{\frac{u0}{\frac{\frac{1}{alphax \cdot alphax}}{1 + \frac{alphay \cdot alphay}{alphax \cdot alphax} \cdot \frac{0.5 - 0.5 \cdot \cos \left(2 \cdot \left(\mathsf{fma}\left(2, u1, 0.5\right) \cdot \mathsf{PI}\left(\right)\right)\right)}{{t\_1}^{2}}} + \frac{{\sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \frac{\sin t\_0}{t\_1}\right)}^{2}}{alphay \cdot alphay}}}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.3%
lift-*.f32N/A
lift-cos.f32N/A
lift-atan.f32N/A
cos-atanN/A
lift-cos.f32N/A
lift-atan.f32N/A
cos-atanN/A
Applied rewrites92.1%
Taylor expanded in u1 around inf
Applied rewrites99.9%
Applied rewrites99.2%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(sqrt
(/
1.0
(+
(/
(/
(* (* alphay alphay) u0)
(pow
(sin
(atan
(*
(/ alphay alphax)
(/ (sin (* (PI) 0.5)) (cos (* (PI) (+ 0.5 (* 2.0 u1))))))))
2.0))
(- 1.0 u0))
1.0))))\begin{array}{l}
\\
\sqrt{\frac{1}{\frac{\frac{\left(alphay \cdot alphay\right) \cdot u0}{{\sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \frac{\sin \left(\mathsf{PI}\left(\right) \cdot 0.5\right)}{\cos \left(\mathsf{PI}\left(\right) \cdot \left(0.5 + 2 \cdot u1\right)\right)}\right)}^{2}}}{1 - u0} + 1}}
\end{array}
Initial program 99.3%
Taylor expanded in u1 around 0
Applied rewrites98.1%
Taylor expanded in alphax around inf
Applied rewrites98.0%
Taylor expanded in u1 around 0
Applied rewrites98.6%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(-
1.0
(/
(* 0.5 (* (* alphay alphay) u0))
(*
(pow
(sin
(atan
(*
(/ alphay alphax)
(/ (sin (* (PI) 0.5)) (cos (* (PI) (+ 0.5 (* 2.0 u1))))))))
2.0)
(- 1.0 u0)))))\begin{array}{l}
\\
1 - \frac{0.5 \cdot \left(\left(alphay \cdot alphay\right) \cdot u0\right)}{{\sin \tan^{-1} \left(\frac{alphay}{alphax} \cdot \frac{\sin \left(\mathsf{PI}\left(\right) \cdot 0.5\right)}{\cos \left(\mathsf{PI}\left(\right) \cdot \left(0.5 + 2 \cdot u1\right)\right)}\right)}^{2} \cdot \left(1 - u0\right)}
\end{array}
Initial program 99.3%
Taylor expanded in u1 around 0
Applied rewrites98.0%
Taylor expanded in u1 around 0
Applied rewrites99.8%
Taylor expanded in alphay around 0
fp-cancel-sign-sub-invN/A
metadata-evalN/A
lower--.f32N/A
associate-*r/N/A
Applied rewrites96.5%
Taylor expanded in u1 around 0
Applied rewrites97.0%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(-
1.0
(/
(* 0.5 (* (* alphay alphay) u0))
(*
(-
0.5
(*
(cos
(* -2.0 (atan (* (tan (* (fma 2.0 u1 0.5) (PI))) (/ alphay alphax)))))
0.5))
(- 1.0 u0)))))\begin{array}{l}
\\
1 - \frac{0.5 \cdot \left(\left(alphay \cdot alphay\right) \cdot u0\right)}{\left(0.5 - \cos \left(-2 \cdot \tan^{-1} \left(\tan \left(\mathsf{fma}\left(2, u1, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\right)\right) \cdot 0.5\right) \cdot \left(1 - u0\right)}
\end{array}
Initial program 99.3%
Taylor expanded in u1 around 0
Applied rewrites98.0%
Taylor expanded in u1 around 0
Applied rewrites99.8%
Taylor expanded in alphay around 0
fp-cancel-sign-sub-invN/A
metadata-evalN/A
lower--.f32N/A
associate-*r/N/A
Applied rewrites96.5%
Applied rewrites76.0%
(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%
Taylor expanded in u0 around 0
Applied rewrites91.3%
herbie shell --seed 2024339
(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))))))