
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * sin(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i u1 u2) :precision binary32 (* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf(-logf((1.0f - u1))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(-log(Float32(Float32(1.0) - u1)))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
function tmp = code(cosTheta_i, u1, u2) tmp = sqrt(-log((single(1.0) - u1))) * sin(((single(2.0) * single(pi)) * u2)); end
\begin{array}{l}
\\
\sqrt{-\log \left(1 - u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
(FPCore (cosTheta_i u1 u2)
:precision binary32
(if (<= u1 0.035999998450279236)
(*
(sqrt
(*
-1.0
(*
(-
(/ (* -1.0 (+ (/ 1.0 u1) 0.5)) (* u1 u1))
(fma (/ 1.0 u1) 0.3333333333333333 0.25))
(pow u1 4.0))))
(sin (* (* 2.0 PI) u2)))
(*
(sqrt (* -1.0 (log (- 1.0 u1))))
(* 2.0 (* (sin (* PI u2)) (cos (* PI u2)))))))
float code(float cosTheta_i, float u1, float u2) {
float tmp;
if (u1 <= 0.035999998450279236f) {
tmp = sqrtf((-1.0f * ((((-1.0f * ((1.0f / u1) + 0.5f)) / (u1 * u1)) - fmaf((1.0f / u1), 0.3333333333333333f, 0.25f)) * powf(u1, 4.0f)))) * sinf(((2.0f * ((float) M_PI)) * u2));
} else {
tmp = sqrtf((-1.0f * logf((1.0f - u1)))) * (2.0f * (sinf((((float) M_PI) * u2)) * cosf((((float) M_PI) * u2))));
}
return tmp;
}
function code(cosTheta_i, u1, u2) tmp = Float32(0.0) if (u1 <= Float32(0.035999998450279236)) tmp = Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(-1.0) * Float32(Float32(Float32(1.0) / u1) + Float32(0.5))) / Float32(u1 * u1)) - fma(Float32(Float32(1.0) / u1), Float32(0.3333333333333333), Float32(0.25))) * (u1 ^ Float32(4.0))))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))); else tmp = Float32(sqrt(Float32(Float32(-1.0) * log(Float32(Float32(1.0) - u1)))) * Float32(Float32(2.0) * Float32(sin(Float32(Float32(pi) * u2)) * cos(Float32(Float32(pi) * u2))))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u1 \leq 0.035999998450279236:\\
\;\;\;\;\sqrt{-1 \cdot \left(\left(\frac{-1 \cdot \left(\frac{1}{u1} + 0.5\right)}{u1 \cdot u1} - \mathsf{fma}\left(\frac{1}{u1}, 0.3333333333333333, 0.25\right)\right) \cdot {u1}^{4}\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-1 \cdot \log \left(1 - u1\right)} \cdot \left(2 \cdot \left(\sin \left(\pi \cdot u2\right) \cdot \cos \left(\pi \cdot u2\right)\right)\right)\\
\end{array}
\end{array}
if u1 < 0.0359999985Initial program 48.2%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3298.4
Applied rewrites98.4%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
+-commutativeN/A
lower-+.f32N/A
lift-/.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lift-/.f32N/A
lower-pow.f3298.4
Applied rewrites98.4%
if 0.0359999985 < u1 Initial program 96.7%
lift-sin.f32N/A
lift-*.f32N/A
lift-PI.f32N/A
lift-*.f32N/A
associate-*l*N/A
*-commutativeN/A
sin-2N/A
lower-*.f32N/A
lower-*.f32N/A
lower-sin.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f32N/A
lower-cos.f32N/A
*-commutativeN/A
lower-*.f32N/A
lift-PI.f3296.7
Applied rewrites96.7%
Final simplification98.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sin (* (* 2.0 PI) u2))))
(if (<= u1 0.035999998450279236)
(*
(sqrt
(*
-1.0
(*
(-
(/ (* -1.0 (+ (/ 1.0 u1) 0.5)) (* u1 u1))
(fma (/ 1.0 u1) 0.3333333333333333 0.25))
(pow u1 4.0))))
t_0)
(* (sqrt (* -1.0 (log (- 1.0 u1)))) t_0))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = sinf(((2.0f * ((float) M_PI)) * u2));
float tmp;
if (u1 <= 0.035999998450279236f) {
tmp = sqrtf((-1.0f * ((((-1.0f * ((1.0f / u1) + 0.5f)) / (u1 * u1)) - fmaf((1.0f / u1), 0.3333333333333333f, 0.25f)) * powf(u1, 4.0f)))) * t_0;
} else {
tmp = sqrtf((-1.0f * logf((1.0f - u1)))) * t_0;
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2)) tmp = Float32(0.0) if (u1 <= Float32(0.035999998450279236)) tmp = Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(-1.0) * Float32(Float32(Float32(1.0) / u1) + Float32(0.5))) / Float32(u1 * u1)) - fma(Float32(Float32(1.0) / u1), Float32(0.3333333333333333), Float32(0.25))) * (u1 ^ Float32(4.0))))) * t_0); else tmp = Float32(sqrt(Float32(Float32(-1.0) * log(Float32(Float32(1.0) - u1)))) * t_0); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)\\
\mathbf{if}\;u1 \leq 0.035999998450279236:\\
\;\;\;\;\sqrt{-1 \cdot \left(\left(\frac{-1 \cdot \left(\frac{1}{u1} + 0.5\right)}{u1 \cdot u1} - \mathsf{fma}\left(\frac{1}{u1}, 0.3333333333333333, 0.25\right)\right) \cdot {u1}^{4}\right)} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-1 \cdot \log \left(1 - u1\right)} \cdot t\_0\\
\end{array}
\end{array}
if u1 < 0.0359999985Initial program 48.2%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3298.4
Applied rewrites98.4%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
+-commutativeN/A
lower-+.f32N/A
lift-/.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lift-/.f32N/A
lower-pow.f3298.4
Applied rewrites98.4%
if 0.0359999985 < u1 Initial program 96.7%
Final simplification98.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (sin (* (* 2.0 PI) u2))))
(if (<= u1 0.03799999877810478)
(*
(sqrt
(*
-1.0
(*
(-
(/ (* -1.0 (+ (/ 1.0 u1) 0.5)) (* u1 u1))
(fma (/ 1.0 u1) 0.3333333333333333 0.25))
(pow u1 4.0))))
t_0)
(* (sqrt (* -1.0 (log (* (- (/ 1.0 u1) 1.0) u1)))) t_0))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = sinf(((2.0f * ((float) M_PI)) * u2));
float tmp;
if (u1 <= 0.03799999877810478f) {
tmp = sqrtf((-1.0f * ((((-1.0f * ((1.0f / u1) + 0.5f)) / (u1 * u1)) - fmaf((1.0f / u1), 0.3333333333333333f, 0.25f)) * powf(u1, 4.0f)))) * t_0;
} else {
tmp = sqrtf((-1.0f * logf((((1.0f / u1) - 1.0f) * u1)))) * t_0;
}
return tmp;
}
function code(cosTheta_i, u1, u2) t_0 = sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2)) tmp = Float32(0.0) if (u1 <= Float32(0.03799999877810478)) tmp = Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(-1.0) * Float32(Float32(Float32(1.0) / u1) + Float32(0.5))) / Float32(u1 * u1)) - fma(Float32(Float32(1.0) / u1), Float32(0.3333333333333333), Float32(0.25))) * (u1 ^ Float32(4.0))))) * t_0); else tmp = Float32(sqrt(Float32(Float32(-1.0) * log(Float32(Float32(Float32(Float32(1.0) / u1) - Float32(1.0)) * u1)))) * t_0); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)\\
\mathbf{if}\;u1 \leq 0.03799999877810478:\\
\;\;\;\;\sqrt{-1 \cdot \left(\left(\frac{-1 \cdot \left(\frac{1}{u1} + 0.5\right)}{u1 \cdot u1} - \mathsf{fma}\left(\frac{1}{u1}, 0.3333333333333333, 0.25\right)\right) \cdot {u1}^{4}\right)} \cdot t\_0\\
\mathbf{else}:\\
\;\;\;\;\sqrt{-1 \cdot \log \left(\left(\frac{1}{u1} - 1\right) \cdot u1\right)} \cdot t\_0\\
\end{array}
\end{array}
if u1 < 0.0379999988Initial program 48.4%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3298.3
Applied rewrites98.3%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
+-commutativeN/A
lower-+.f32N/A
lift-/.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lift-/.f32N/A
lower-pow.f3298.4
Applied rewrites98.4%
if 0.0379999988 < u1 Initial program 96.7%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-/.f3296.2
Applied rewrites96.2%
Final simplification98.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5)))
(*
(sqrt
(*
-1.0
(*
(/
(- (* (* t_0 u1) (* (- (* -0.3333333333333333 u1) 0.5) u1)) 1.0)
(fma t_0 u1 1.0))
u1)))
(sin (* (* 2.0 PI) u2)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = (((-0.25f * u1) - 0.3333333333333333f) * u1) - 0.5f;
return sqrtf((-1.0f * (((((t_0 * u1) * (((-0.3333333333333333f * u1) - 0.5f) * u1)) - 1.0f) / fmaf(t_0, u1, 1.0f)) * u1))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) t_0 = Float32(Float32(Float32(Float32(Float32(-0.25) * u1) - Float32(0.3333333333333333)) * u1) - Float32(0.5)) return Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(t_0 * u1) * Float32(Float32(Float32(Float32(-0.3333333333333333) * u1) - Float32(0.5)) * u1)) - Float32(1.0)) / fma(t_0, u1, Float32(1.0))) * u1))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\\
\sqrt{-1 \cdot \left(\frac{\left(t\_0 \cdot u1\right) \cdot \left(\left(-0.3333333333333333 \cdot u1 - 0.5\right) \cdot u1\right) - 1}{\mathsf{fma}\left(t\_0, u1, 1\right)} \cdot u1\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
\end{array}
Initial program 54.8%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
lift--.f32N/A
lift-*.f32N/A
lift--.f32N/A
lift-*.f32N/A
lift--.f32N/A
lift-*.f32N/A
flip--N/A
lower-/.f32N/A
Applied rewrites94.0%
Taylor expanded in u1 around 0
Applied rewrites94.8%
Final simplification94.8%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(*
(sqrt
(*
-1.0
(*
(-
(/ (* -1.0 (+ (/ 1.0 u1) 0.5)) (* u1 u1))
(fma (/ 1.0 u1) 0.3333333333333333 0.25))
(pow u1 4.0))))
(sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf((-1.0f * ((((-1.0f * ((1.0f / u1) + 0.5f)) / (u1 * u1)) - fmaf((1.0f / u1), 0.3333333333333333f, 0.25f)) * powf(u1, 4.0f)))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(-1.0) * Float32(Float32(Float32(1.0) / u1) + Float32(0.5))) / Float32(u1 * u1)) - fma(Float32(Float32(1.0) / u1), Float32(0.3333333333333333), Float32(0.25))) * (u1 ^ Float32(4.0))))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
\begin{array}{l}
\\
\sqrt{-1 \cdot \left(\left(\frac{-1 \cdot \left(\frac{1}{u1} + 0.5\right)}{u1 \cdot u1} - \mathsf{fma}\left(\frac{1}{u1}, 0.3333333333333333, 0.25\right)\right) \cdot {u1}^{4}\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Initial program 54.8%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
+-commutativeN/A
lower-+.f32N/A
lift-/.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lift-/.f32N/A
lower-pow.f3294.2
Applied rewrites94.2%
Final simplification94.2%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(*
(sqrt
(*
-1.0
(*
(-
(/ (- (* -0.5 u1) 1.0) (pow u1 3.0))
(fma (/ 1.0 u1) 0.3333333333333333 0.25))
(pow u1 4.0))))
(sin (* (* 2.0 PI) u2))))
float code(float cosTheta_i, float u1, float u2) {
return sqrtf((-1.0f * (((((-0.5f * u1) - 1.0f) / powf(u1, 3.0f)) - fmaf((1.0f / u1), 0.3333333333333333f, 0.25f)) * powf(u1, 4.0f)))) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) return Float32(sqrt(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(Float32(-0.5) * u1) - Float32(1.0)) / (u1 ^ Float32(3.0))) - fma(Float32(Float32(1.0) / u1), Float32(0.3333333333333333), Float32(0.25))) * (u1 ^ Float32(4.0))))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
\begin{array}{l}
\\
\sqrt{-1 \cdot \left(\left(\frac{-0.5 \cdot u1 - 1}{{u1}^{3}} - \mathsf{fma}\left(\frac{1}{u1}, 0.3333333333333333, 0.25\right)\right) \cdot {u1}^{4}\right)} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
Initial program 54.8%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
Taylor expanded in u1 around inf
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
associate-*r/N/A
lower-/.f32N/A
lower-*.f32N/A
+-commutativeN/A
lower-+.f32N/A
lift-/.f32N/A
unpow2N/A
lower-*.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lift-/.f32N/A
lower-pow.f3294.2
Applied rewrites94.2%
Taylor expanded in u1 around 0
lower-/.f32N/A
lower--.f32N/A
lower-*.f32N/A
lift-pow.f3294.1
Applied rewrites94.1%
Final simplification94.1%
(FPCore (cosTheta_i u1 u2)
:precision binary32
(let* ((t_0 (- (* (- (* -0.25 u1) 0.3333333333333333) u1) 0.5))
(t_1 (fma t_0 u1 1.0)))
(*
(exp
(*
(log
(*
-1.0
(*
(-
(/ (* (* t_0 u1) (* (- (* -0.3333333333333333 u1) 0.5) u1)) t_1)
(/ 1.0 t_1))
u1)))
0.5))
(sin (* (* 2.0 PI) u2)))))
float code(float cosTheta_i, float u1, float u2) {
float t_0 = (((-0.25f * u1) - 0.3333333333333333f) * u1) - 0.5f;
float t_1 = fmaf(t_0, u1, 1.0f);
return expf((logf((-1.0f * (((((t_0 * u1) * (((-0.3333333333333333f * u1) - 0.5f) * u1)) / t_1) - (1.0f / t_1)) * u1))) * 0.5f)) * sinf(((2.0f * ((float) M_PI)) * u2));
}
function code(cosTheta_i, u1, u2) t_0 = Float32(Float32(Float32(Float32(Float32(-0.25) * u1) - Float32(0.3333333333333333)) * u1) - Float32(0.5)) t_1 = fma(t_0, u1, Float32(1.0)) return Float32(exp(Float32(log(Float32(Float32(-1.0) * Float32(Float32(Float32(Float32(Float32(t_0 * u1) * Float32(Float32(Float32(Float32(-0.3333333333333333) * u1) - Float32(0.5)) * u1)) / t_1) - Float32(Float32(1.0) / t_1)) * u1))) * Float32(0.5))) * sin(Float32(Float32(Float32(2.0) * Float32(pi)) * u2))) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(-0.25 \cdot u1 - 0.3333333333333333\right) \cdot u1 - 0.5\\
t_1 := \mathsf{fma}\left(t\_0, u1, 1\right)\\
e^{\log \left(-1 \cdot \left(\left(\frac{\left(t\_0 \cdot u1\right) \cdot \left(\left(-0.3333333333333333 \cdot u1 - 0.5\right) \cdot u1\right)}{t\_1} - \frac{1}{t\_1}\right) \cdot u1\right)\right) \cdot 0.5} \cdot \sin \left(\left(2 \cdot \pi\right) \cdot u2\right)
\end{array}
\end{array}
Initial program 54.8%
Taylor expanded in u1 around 0
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower--.f32N/A
lower-*.f3294.1
Applied rewrites94.1%
lift--.f32N/A
lift-*.f32N/A
lift--.f32N/A
lift-*.f32N/A
lift--.f32N/A
lift-*.f32N/A
flip--N/A
lower-/.f32N/A
Applied rewrites94.0%
Taylor expanded in u1 around 0
Applied rewrites94.8%
Applied rewrites92.6%
Final simplification92.6%
herbie shell --seed 2025064
(FPCore (cosTheta_i u1 u2)
:name "Beckmann Sample, near normal, slope_y"
:precision binary32
:pre (and (and (and (> cosTheta_i 0.9999) (<= cosTheta_i 1.0)) (and (<= 2.328306437e-10 u1) (<= u1 1.0))) (and (<= 2.328306437e-10 u2) (<= u2 1.0)))
(* (sqrt (- (log (- 1.0 u1)))) (sin (* (* 2.0 PI) u2))))