
(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 9 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 u1 2.0 0.5))) (/ alphay alphax))))
(exp
(*
-0.5
(log1p
(/
u0
(*
(- 1.0 u0)
(fma
(/ 0.5 (* alphay alphay))
(- 1.0 (cos (* (atan t_0) 2.0)))
(/ 1.0 (* (* alphax alphax) (+ (pow t_0 2.0) 1.0)))))))))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax);
return expf((-0.5f * log1pf((u0 / ((1.0f - u0) * fmaf((0.5f / (alphay * alphay)), (1.0f - cosf((atanf(t_0) * 2.0f))), (1.0f / ((alphax * alphax) * (powf(t_0, 2.0f) + 1.0f)))))))));
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax)) return exp(Float32(Float32(-0.5) * log1p(Float32(u0 / Float32(Float32(Float32(1.0) - u0) * fma(Float32(Float32(0.5) / Float32(alphay * alphay)), Float32(Float32(1.0) - cos(Float32(atan(t_0) * Float32(2.0)))), Float32(Float32(1.0) / Float32(Float32(alphax * alphax) * Float32((t_0 ^ Float32(2.0)) + Float32(1.0)))))))))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\\
e^{-0.5 \cdot \mathsf{log1p}\left(\frac{u0}{\left(1 - u0\right) \cdot \mathsf{fma}\left(\frac{0.5}{alphay \cdot alphay}, 1 - \cos \left(\tan^{-1} t\_0 \cdot 2\right), \frac{1}{\left(alphax \cdot alphax\right) \cdot \left({t\_0}^{2} + 1\right)}\right)}\right)}
\end{array}
\end{array}
Initial program 99.3%
Applied rewrites99.3%
Applied rewrites100.0%
Final simplification100.0%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* (tan (* PI (fma u1 2.0 0.5))) (/ alphay alphax))))
(pow
(+
(/
u0
(*
(- 1.0 u0)
(fma
(/ 0.5 (* alphay alphay))
(- 1.0 (cos (* (atan t_0) 2.0)))
(/ 1.0 (* (* alphax alphax) (+ (pow t_0 2.0) 1.0))))))
1.0)
-0.5)))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax);
return powf(((u0 / ((1.0f - u0) * fmaf((0.5f / (alphay * alphay)), (1.0f - cosf((atanf(t_0) * 2.0f))), (1.0f / ((alphax * alphax) * (powf(t_0, 2.0f) + 1.0f)))))) + 1.0f), -0.5f);
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax)) return Float32(Float32(u0 / Float32(Float32(Float32(1.0) - u0) * fma(Float32(Float32(0.5) / Float32(alphay * alphay)), Float32(Float32(1.0) - cos(Float32(atan(t_0) * Float32(2.0)))), Float32(Float32(1.0) / Float32(Float32(alphax * alphax) * Float32((t_0 ^ Float32(2.0)) + Float32(1.0))))))) + Float32(1.0)) ^ Float32(-0.5) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\\
{\left(\frac{u0}{\left(1 - u0\right) \cdot \mathsf{fma}\left(\frac{0.5}{alphay \cdot alphay}, 1 - \cos \left(\tan^{-1} t\_0 \cdot 2\right), \frac{1}{\left(alphax \cdot alphax\right) \cdot \left({t\_0}^{2} + 1\right)}\right)} + 1\right)}^{-0.5}
\end{array}
\end{array}
Initial program 99.3%
Applied rewrites99.3%
Applied rewrites99.9%
Final simplification99.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(let* ((t_0 (* (tan (* PI (fma u1 2.0 0.5))) (/ alphay alphax))))
(/
1.0
(sqrt
(+
(/
u0
(*
(- 1.0 u0)
(fma
(/ 0.5 (* alphay alphay))
(- 1.0 (cos (* (atan t_0) 2.0)))
(/ 1.0 (* (* alphax alphax) (+ (pow t_0 2.0) 1.0))))))
1.0)))))
float code(float u0, float u1, float alphax, float alphay) {
float t_0 = tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax);
return 1.0f / sqrtf(((u0 / ((1.0f - u0) * fmaf((0.5f / (alphay * alphay)), (1.0f - cosf((atanf(t_0) * 2.0f))), (1.0f / ((alphax * alphax) * (powf(t_0, 2.0f) + 1.0f)))))) + 1.0f));
}
function code(u0, u1, alphax, alphay) t_0 = Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax)) return Float32(Float32(1.0) / sqrt(Float32(Float32(u0 / Float32(Float32(Float32(1.0) - u0) * fma(Float32(Float32(0.5) / Float32(alphay * alphay)), Float32(Float32(1.0) - cos(Float32(atan(t_0) * Float32(2.0)))), Float32(Float32(1.0) / Float32(Float32(alphax * alphax) * Float32((t_0 ^ Float32(2.0)) + Float32(1.0))))))) + Float32(1.0)))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\\
\frac{1}{\sqrt{\frac{u0}{\left(1 - u0\right) \cdot \mathsf{fma}\left(\frac{0.5}{alphay \cdot alphay}, 1 - \cos \left(\tan^{-1} t\_0 \cdot 2\right), \frac{1}{\left(alphax \cdot alphax\right) \cdot \left({t\_0}^{2} + 1\right)}\right)} + 1}}
\end{array}
\end{array}
Initial program 99.3%
Applied rewrites99.3%
Applied rewrites99.3%
Final simplification99.3%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(exp
(*
(log1p
(/
(* (* alphay alphay) u0)
(*
(*
(-
1.0
(cos
(* (atan (* (tan (* PI (fma u1 2.0 0.5))) (/ alphay alphax))) 2.0)))
0.5)
(- 1.0 u0))))
-0.5)))
float code(float u0, float u1, float alphax, float alphay) {
return expf((log1pf((((alphay * alphay) * u0) / (((1.0f - cosf((atanf((tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax))) * 2.0f))) * 0.5f) * (1.0f - u0)))) * -0.5f));
}
function code(u0, u1, alphax, alphay) return exp(Float32(log1p(Float32(Float32(Float32(alphay * alphay) * u0) / Float32(Float32(Float32(Float32(1.0) - cos(Float32(atan(Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax))) * Float32(2.0)))) * Float32(0.5)) * Float32(Float32(1.0) - u0)))) * Float32(-0.5))) end
\begin{array}{l}
\\
e^{\mathsf{log1p}\left(\frac{\left(alphay \cdot alphay\right) \cdot u0}{\left(\left(1 - \cos \left(\tan^{-1} \left(\tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right)\right) \cdot 0.5\right) \cdot \left(1 - u0\right)}\right) \cdot -0.5}
\end{array}
Initial program 99.3%
Taylor expanded in alphax around inf
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.9%
Applied rewrites98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(pow
(+
(/
(* (* alphay alphay) u0)
(*
(*
(-
1.0
(cos
(* (atan (* (tan (* PI (fma u1 2.0 0.5))) (/ alphay alphax))) 2.0)))
0.5)
(- 1.0 u0)))
1.0)
-0.5))
float code(float u0, float u1, float alphax, float alphay) {
return powf(((((alphay * alphay) * u0) / (((1.0f - cosf((atanf((tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax))) * 2.0f))) * 0.5f) * (1.0f - u0))) + 1.0f), -0.5f);
}
function code(u0, u1, alphax, alphay) return Float32(Float32(Float32(Float32(alphay * alphay) * u0) / Float32(Float32(Float32(Float32(1.0) - cos(Float32(atan(Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax))) * Float32(2.0)))) * Float32(0.5)) * Float32(Float32(1.0) - u0))) + Float32(1.0)) ^ Float32(-0.5) end
\begin{array}{l}
\\
{\left(\frac{\left(alphay \cdot alphay\right) \cdot u0}{\left(\left(1 - \cos \left(\tan^{-1} \left(\tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right)\right) \cdot 0.5\right) \cdot \left(1 - u0\right)} + 1\right)}^{-0.5}
\end{array}
Initial program 99.3%
Taylor expanded in alphax around inf
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.9%
Applied rewrites98.4%
Final simplification98.4%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(pow
(+
(/
(* (* alphay alphay) u0)
(*
(-
0.5
(* (cos (* (atan (* (/ (tan (* PI 0.5)) alphax) alphay)) 2.0)) 0.5))
(- 1.0 u0)))
1.0)
-0.5))
float code(float u0, float u1, float alphax, float alphay) {
return powf(((((alphay * alphay) * u0) / ((0.5f - (cosf((atanf(((tanf((((float) M_PI) * 0.5f)) / alphax) * alphay)) * 2.0f)) * 0.5f)) * (1.0f - u0))) + 1.0f), -0.5f);
}
function code(u0, u1, alphax, alphay) return Float32(Float32(Float32(Float32(alphay * alphay) * u0) / Float32(Float32(Float32(0.5) - Float32(cos(Float32(atan(Float32(Float32(tan(Float32(Float32(pi) * Float32(0.5))) / alphax) * alphay)) * Float32(2.0))) * Float32(0.5))) * Float32(Float32(1.0) - u0))) + Float32(1.0)) ^ Float32(-0.5) end
function tmp = code(u0, u1, alphax, alphay) tmp = ((((alphay * alphay) * u0) / ((single(0.5) - (cos((atan(((tan((single(pi) * single(0.5))) / alphax) * alphay)) * single(2.0))) * single(0.5))) * (single(1.0) - u0))) + single(1.0)) ^ single(-0.5); end
\begin{array}{l}
\\
{\left(\frac{\left(alphay \cdot alphay\right) \cdot u0}{\left(0.5 - \cos \left(\tan^{-1} \left(\frac{\tan \left(\pi \cdot 0.5\right)}{alphax} \cdot alphay\right) \cdot 2\right) \cdot 0.5\right) \cdot \left(1 - u0\right)} + 1\right)}^{-0.5}
\end{array}
Initial program 99.3%
Taylor expanded in alphax around inf
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.9%
Taylor expanded in u1 around 0
Applied rewrites97.4%
Applied rewrites97.9%
Final simplification97.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
(/
(* (* alphay alphay) u0)
(*
(*
(-
1.0
(cos
(* (atan (* (tan (* PI (fma u1 2.0 0.5))) (/ alphay alphax))) 2.0)))
0.5)
(- 1.0 u0)))
1.0))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf(((((alphay * alphay) * u0) / (((1.0f - cosf((atanf((tanf((((float) M_PI) * fmaf(u1, 2.0f, 0.5f))) * (alphay / alphax))) * 2.0f))) * 0.5f) * (1.0f - u0))) + 1.0f));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(Float32(Float32(alphay * alphay) * u0) / Float32(Float32(Float32(Float32(1.0) - cos(Float32(atan(Float32(tan(Float32(Float32(pi) * fma(u1, Float32(2.0), Float32(0.5)))) * Float32(alphay / alphax))) * Float32(2.0)))) * Float32(0.5)) * Float32(Float32(1.0) - u0))) + Float32(1.0)))) end
\begin{array}{l}
\\
\frac{1}{\sqrt{\frac{\left(alphay \cdot alphay\right) \cdot u0}{\left(\left(1 - \cos \left(\tan^{-1} \left(\tan \left(\pi \cdot \mathsf{fma}\left(u1, 2, 0.5\right)\right) \cdot \frac{alphay}{alphax}\right) \cdot 2\right)\right) \cdot 0.5\right) \cdot \left(1 - u0\right)} + 1}}
\end{array}
Initial program 99.3%
Taylor expanded in alphax around inf
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.9%
Applied rewrites97.9%
Final simplification97.9%
(FPCore (u0 u1 alphax alphay)
:precision binary32
(/
1.0
(sqrt
(+
(/
(* (* alphay alphay) u0)
(*
(-
0.5
(* (cos (* (atan (* (/ (tan (* PI 0.5)) alphax) alphay)) 2.0)) 0.5))
(- 1.0 u0)))
1.0))))
float code(float u0, float u1, float alphax, float alphay) {
return 1.0f / sqrtf(((((alphay * alphay) * u0) / ((0.5f - (cosf((atanf(((tanf((((float) M_PI) * 0.5f)) / alphax) * alphay)) * 2.0f)) * 0.5f)) * (1.0f - u0))) + 1.0f));
}
function code(u0, u1, alphax, alphay) return Float32(Float32(1.0) / sqrt(Float32(Float32(Float32(Float32(alphay * alphay) * u0) / Float32(Float32(Float32(0.5) - Float32(cos(Float32(atan(Float32(Float32(tan(Float32(Float32(pi) * Float32(0.5))) / alphax) * alphay)) * Float32(2.0))) * Float32(0.5))) * Float32(Float32(1.0) - u0))) + Float32(1.0)))) end
function tmp = code(u0, u1, alphax, alphay) tmp = single(1.0) / sqrt(((((alphay * alphay) * u0) / ((single(0.5) - (cos((atan(((tan((single(pi) * single(0.5))) / alphax) * alphay)) * single(2.0))) * single(0.5))) * (single(1.0) - u0))) + single(1.0))); end
\begin{array}{l}
\\
\frac{1}{\sqrt{\frac{\left(alphay \cdot alphay\right) \cdot u0}{\left(0.5 - \cos \left(\tan^{-1} \left(\frac{\tan \left(\pi \cdot 0.5\right)}{alphax} \cdot alphay\right) \cdot 2\right) \cdot 0.5\right) \cdot \left(1 - u0\right)} + 1}}
\end{array}
Initial program 99.3%
Taylor expanded in alphax around inf
lower-/.f32N/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
lower-*.f32N/A
Applied rewrites97.9%
Taylor expanded in u1 around 0
Applied rewrites97.4%
Applied rewrites97.4%
Final simplification97.4%
(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 alphax around 0
lower-/.f32N/A
*-commutativeN/A
lower-*.f32N/A
unpow2N/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-pow.f32N/A
Applied rewrites51.0%
Taylor expanded in alphax around 0
Applied rewrites90.4%
herbie shell --seed 2024235
(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))))))