
(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 10 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
(atan
(* (tan (+ (* 0.5 (PI)) (* u1 (* (PI) 2.0)))) (/ alphay alphax))))
(t_1 (cos t_0))
(t_2 (sin t_0)))
(/
1.0
(sqrt
(-
1.0
(/
(*
(/
-1.0
(+
(/ (* t_2 t_2) (* alphay alphay))
(/ (* t_1 t_1) (* alphax alphax))))
u0)
(- 1.0 u0)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\tan \left(0.5 \cdot \mathsf{PI}\left(\right) + u1 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot \frac{alphay}{alphax}\right)\\
t_1 := \cos t\_0\\
t_2 := \sin t\_0\\
\frac{1}{\sqrt{1 - \frac{\frac{-1}{\frac{t\_2 \cdot t\_2}{alphay \cdot alphay} + \frac{t\_1 \cdot t\_1}{alphax \cdot alphax}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.4%
Final simplification99.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* 0.5 (PI)))
(t_1 (atan (* (tan (+ t_0 (* u1 (* (PI) 2.0)))) (/ alphay alphax))))
(t_2 (cos t_1)))
(/
1.0
(sqrt
(-
1.0
(/
(*
(/
-1.0
(+
(/
(* (sin (atan (* (tan t_0) (/ alphay alphax)))) (sin t_1))
(* alphay alphay))
(/ (* t_2 t_2) (* alphax alphax))))
u0)
(- 1.0 u0)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := 0.5 \cdot \mathsf{PI}\left(\right)\\
t_1 := \tan^{-1} \left(\tan \left(t\_0 + u1 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot \frac{alphay}{alphax}\right)\\
t_2 := \cos t\_1\\
\frac{1}{\sqrt{1 - \frac{\frac{-1}{\frac{\sin \tan^{-1} \left(\tan t\_0 \cdot \frac{alphay}{alphax}\right) \cdot \sin t\_1}{alphay \cdot alphay} + \frac{t\_2 \cdot t\_2}{alphax \cdot alphax}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3298.4
Applied rewrites98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* (+ (* u1 2.0) 0.5) (PI))) (t_1 (cos t_0)))
(sqrt
(/
1.0
(-
1.0
(/
(/ u0 (- u0 1.0))
(+
(/
(pow
(cos
(atan
(/ (* (sin (* (fma u1 2.0 0.5) (PI))) (/ alphay alphax)) t_1)))
2.0)
(* alphax alphax))
(/
(pow (sin (atan (/ (* (sin t_0) (/ alphay alphax)) t_1))) 2.0)
(* alphay alphay)))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(u1 \cdot 2 + 0.5\right) \cdot \mathsf{PI}\left(\right)\\
t_1 := \cos t\_0\\
\sqrt{\frac{1}{1 - \frac{\frac{u0}{u0 - 1}}{\frac{{\cos \tan^{-1} \left(\frac{\sin \left(\mathsf{fma}\left(u1, 2, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}}{t\_1}\right)}^{2}}{alphax \cdot alphax} + \frac{{\sin \tan^{-1} \left(\frac{\sin t\_0 \cdot \frac{alphay}{alphax}}{t\_1}\right)}^{2}}{alphay \cdot alphay}}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
Applied rewrites98.4%
Applied rewrites98.8%
Applied rewrites99.1%
Applied rewrites98.8%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (cos (* (+ (* u1 2.0) 0.5) (PI)))))
(sqrt
(/
1.0
(-
1.0
(/
(/ u0 (- u0 1.0))
(+
(/
(pow
(cos (atan (/ (* (sin (* 0.5 (PI))) (/ alphay alphax)) t_0)))
2.0)
(* alphax alphax))
(/
(pow
(sin
(atan
(/ (* (sin (* (fma u1 2.0 0.5) (PI))) (/ alphay alphax)) t_0)))
2.0)
(* alphay alphay)))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos \left(\left(u1 \cdot 2 + 0.5\right) \cdot \mathsf{PI}\left(\right)\right)\\
\sqrt{\frac{1}{1 - \frac{\frac{u0}{u0 - 1}}{\frac{{\cos \tan^{-1} \left(\frac{\sin \left(0.5 \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}}{t\_0}\right)}^{2}}{alphax \cdot alphax} + \frac{{\sin \tan^{-1} \left(\frac{\sin \left(\mathsf{fma}\left(u1, 2, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}}{t\_0}\right)}^{2}}{alphay \cdot alphay}}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
Applied rewrites98.4%
Applied rewrites98.8%
Applied rewrites99.1%
Taylor expanded in u1 around 0
Applied rewrites99.1%
Final simplification70.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* (sin (* (fma u1 2.0 0.5) (PI))) (/ alphay alphax))))
(sqrt
(/
1.0
(-
1.0
(/
(/ u0 (- u0 1.0))
(+
(/ (pow (sin (atan (/ t_0 (cos (* 0.5 (PI)))))) 2.0) (* alphay alphay))
(/
(pow (cos (atan (/ t_0 (cos (* (+ (* u1 2.0) 0.5) (PI)))))) 2.0)
(* alphax alphax)))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\mathsf{fma}\left(u1, 2, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\\
\sqrt{\frac{1}{1 - \frac{\frac{u0}{u0 - 1}}{\frac{{\sin \tan^{-1} \left(\frac{t\_0}{\cos \left(0.5 \cdot \mathsf{PI}\left(\right)\right)}\right)}^{2}}{alphay \cdot alphay} + \frac{{\cos \tan^{-1} \left(\frac{t\_0}{\cos \left(\left(u1 \cdot 2 + 0.5\right) \cdot \mathsf{PI}\left(\right)\right)}\right)}^{2}}{alphax \cdot alphax}}}}
\end{array}
\end{array}
Initial program 99.4%
Taylor expanded in u1 around 0
Applied rewrites98.4%
Applied rewrites98.8%
Applied rewrites99.1%
Taylor expanded in u1 around 0
Applied rewrites98.7%
Final simplification98.7%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0
(sin
(atan
(* (tan (+ (* 0.5 (PI)) (* u1 (* (PI) 2.0)))) (/ alphay alphax))))))
(/
1.0
(sqrt
(-
1.0
(/
(*
(/
-1.0
(+
(/
(+
(*
(cos
(*
(atan (* (tan (* (fma u1 2.0 0.5) (PI))) (/ alphay alphax)))
2.0))
0.5)
0.5)
(* alphax alphax))
(/ (* t_0 t_0) (* alphay alphay))))
u0)
(- 1.0 u0)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \tan^{-1} \left(\tan \left(0.5 \cdot \mathsf{PI}\left(\right) + u1 \cdot \left(\mathsf{PI}\left(\right) \cdot 2\right)\right) \cdot \frac{alphay}{alphax}\right)\\
\frac{1}{\sqrt{1 - \frac{\frac{-1}{\frac{\cos \left(\tan^{-1} \left(\tan \left(\mathsf{fma}\left(u1, 2, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right) \cdot 0.5 + 0.5}{alphax \cdot alphax} + \frac{t\_0 \cdot t\_0}{alphay \cdot alphay}} \cdot u0}{1 - u0}}}
\end{array}
\end{array}
Initial program 99.4%
lift-*.f32N/A
lift-cos.f32N/A
lift-cos.f32N/A
sqr-cos-aN/A
+-commutativeN/A
Applied rewrites91.4%
lift-fma.f32N/A
lower-+.f32N/A
Applied rewrites98.3%
Final simplification98.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (atan (* (tan (* (fma u1 2.0 0.5) (PI))) (/ alphay alphax)))))
(sqrt
(/
1.0
(-
1.0
(/
(/ u0 (- u0 1.0))
(+ (pow (/ (cos t_0) alphax) 2.0) (pow (/ (sin t_0) alphay) 2.0))))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan^{-1} \left(\tan \left(\mathsf{fma}\left(u1, 2, 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\right)\\
\sqrt{\frac{1}{1 - \frac{\frac{u0}{u0 - 1}}{{\left(\frac{\cos t\_0}{alphax}\right)}^{2} + {\left(\frac{\sin t\_0}{alphay}\right)}^{2}}}}
\end{array}
\end{array}
Initial program 99.4%
Applied rewrites52.4%
Applied rewrites98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(-
1.0
(/
(* u0 (* alphay alphay))
(*
(-
(cos
(* (atan (* (tan (* (+ (* u1 2.0) 0.5) (PI))) (/ alphay alphax))) 2.0))
1.0)
(- u0 1.0)))))\begin{array}{l}
\\
1 - \frac{u0 \cdot \left(alphay \cdot alphay\right)}{\left(\cos \left(\tan^{-1} \left(\tan \left(\left(u1 \cdot 2 + 0.5\right) \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right) - 1\right) \cdot \left(u0 - 1\right)}
\end{array}
Initial program 99.4%
Applied rewrites52.4%
Taylor expanded in alphay around 0
Applied rewrites74.2%
Applied rewrites73.5%
Applied rewrites95.9%
Final simplification95.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(-
1.0
(/
(* u0 (* alphay alphay))
(*
(- (cos (* (atan (* (tan (* 0.5 (PI))) (/ alphay alphax))) 2.0)) 1.0)
(- u0 1.0)))))\begin{array}{l}
\\
1 - \frac{u0 \cdot \left(alphay \cdot alphay\right)}{\left(\cos \left(\tan^{-1} \left(\tan \left(0.5 \cdot \mathsf{PI}\left(\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right) - 1\right) \cdot \left(u0 - 1\right)}
\end{array}
Initial program 99.4%
Applied rewrites52.4%
Taylor expanded in alphay around 0
Applied rewrites74.2%
Applied rewrites73.5%
Taylor expanded in u1 around 0
Applied rewrites95.7%
Final simplification95.7%
(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 alphax around 0
Applied rewrites90.4%
herbie shell --seed 2024255
(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))))))