
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (/ 1.0 (sqrt PI)) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta))
(exp (* (- cosTheta) cosTheta))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (((1.0f / sqrtf(((float) M_PI))) * (sqrtf(((1.0f - cosTheta) - cosTheta)) / cosTheta)) * expf((-cosTheta * cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(Float32(Float32(Float32(1.0) / sqrt(Float32(pi))) * Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp(Float32(Float32(-cosTheta) * cosTheta))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (((single(1.0) / sqrt(single(pi))) * (sqrt(((single(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp((-cosTheta * cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{1}{\sqrt{\pi}} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 9 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (/ 1.0 (sqrt PI)) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta))
(exp (* (- cosTheta) cosTheta))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (((1.0f / sqrtf(((float) M_PI))) * (sqrtf(((1.0f - cosTheta) - cosTheta)) / cosTheta)) * expf((-cosTheta * cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(Float32(Float32(Float32(1.0) / sqrt(Float32(pi))) * Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp(Float32(Float32(-cosTheta) * cosTheta))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (((single(1.0) / sqrt(single(pi))) * (sqrt(((single(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp((-cosTheta * cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{1}{\sqrt{\pi}} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{\left(-cosTheta\right) \cdot cosTheta}}
\end{array}
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(fma
(/ (sqrt (+ 1.0 (* cosTheta -2.0))) (* cosTheta (sqrt PI)))
(pow (exp (- cosTheta)) cosTheta)
c))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + fmaf((sqrtf((1.0f + (cosTheta * -2.0f))) / (cosTheta * sqrtf(((float) M_PI)))), powf(expf(-cosTheta), cosTheta), c));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + fma(Float32(sqrt(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0)))) / Float32(cosTheta * sqrt(Float32(pi)))), (exp(Float32(-cosTheta)) ^ cosTheta), c))) end
\begin{array}{l}
\\
\frac{1}{1 + \mathsf{fma}\left(\frac{\sqrt{1 + cosTheta \cdot -2}}{cosTheta \cdot \sqrt{\pi}}, {\left(e^{-cosTheta}\right)}^{cosTheta}, c\right)}
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
Final simplification98.2%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(fma
(/ (sqrt (* cosTheta (- (/ 1.0 (* cosTheta PI)) (/ 2.0 PI)))) cosTheta)
(pow (exp (- cosTheta)) cosTheta)
c))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + fmaf((sqrtf((cosTheta * ((1.0f / (cosTheta * ((float) M_PI))) - (2.0f / ((float) M_PI))))) / cosTheta), powf(expf(-cosTheta), cosTheta), c));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + fma(Float32(sqrt(Float32(cosTheta * Float32(Float32(Float32(1.0) / Float32(cosTheta * Float32(pi))) - Float32(Float32(2.0) / Float32(pi))))) / cosTheta), (exp(Float32(-cosTheta)) ^ cosTheta), c))) end
\begin{array}{l}
\\
\frac{1}{1 + \mathsf{fma}\left(\frac{\sqrt{cosTheta \cdot \left(\frac{1}{cosTheta \cdot \pi} - \frac{2}{\pi}\right)}}{cosTheta}, {\left(e^{-cosTheta}\right)}^{cosTheta}, c\right)}
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
*-un-lft-identity98.2%
associate-/r*97.6%
sqrt-undiv97.7%
+-commutative97.7%
fma-define97.7%
Applied egg-rr97.7%
*-lft-identity97.7%
Simplified97.7%
Taylor expanded in cosTheta around inf 97.7%
*-commutative97.7%
associate-*r/97.7%
metadata-eval97.7%
Simplified97.7%
Final simplification97.7%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(fma
(/ (sqrt (+ (* -2.0 (/ cosTheta PI)) (/ 1.0 PI))) cosTheta)
(pow (exp (- cosTheta)) cosTheta)
c))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + fmaf((sqrtf(((-2.0f * (cosTheta / ((float) M_PI))) + (1.0f / ((float) M_PI)))) / cosTheta), powf(expf(-cosTheta), cosTheta), c));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + fma(Float32(sqrt(Float32(Float32(Float32(-2.0) * Float32(cosTheta / Float32(pi))) + Float32(Float32(1.0) / Float32(pi)))) / cosTheta), (exp(Float32(-cosTheta)) ^ cosTheta), c))) end
\begin{array}{l}
\\
\frac{1}{1 + \mathsf{fma}\left(\frac{\sqrt{-2 \cdot \frac{cosTheta}{\pi} + \frac{1}{\pi}}}{cosTheta}, {\left(e^{-cosTheta}\right)}^{cosTheta}, c\right)}
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
*-un-lft-identity98.2%
associate-/r*97.6%
sqrt-undiv97.7%
+-commutative97.7%
fma-define97.7%
Applied egg-rr97.7%
*-lft-identity97.7%
Simplified97.7%
Taylor expanded in cosTheta around 0 97.7%
Final simplification97.7%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (pow PI -0.5) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta))
(exp (* cosTheta (- cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + ((powf(((float) M_PI), -0.5f) * (sqrtf(((1.0f - cosTheta) - cosTheta)) / cosTheta)) * expf((cosTheta * -cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(Float32((Float32(pi) ^ Float32(-0.5)) * Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp(Float32(cosTheta * Float32(-cosTheta)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (((single(pi) ^ single(-0.5)) * (sqrt(((single(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp((cosTheta * -cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left({\pi}^{-0.5} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{cosTheta \cdot \left(-cosTheta\right)}}
\end{array}
Initial program 97.6%
*-un-lft-identity97.6%
inv-pow97.6%
sqrt-pow297.6%
metadata-eval97.6%
Applied egg-rr97.6%
*-lft-identity97.6%
Simplified97.6%
Final simplification97.6%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(*
(/ (exp (- (pow cosTheta 2.0))) cosTheta)
(sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + ((expf(-powf(cosTheta, 2.0f)) / cosTheta) * sqrtf(((1.0f + (cosTheta * -2.0f)) / ((float) M_PI)))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(exp(Float32(-(cosTheta ^ Float32(2.0)))) / cosTheta) * sqrt(Float32(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0))) / Float32(pi)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + ((exp(-(cosTheta ^ single(2.0))) / cosTheta) * sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi))))); end
\begin{array}{l}
\\
\frac{1}{1 + \frac{e^{-{cosTheta}^{2}}}{cosTheta} \cdot \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}}}
\end{array}
Initial program 97.6%
add-cube-cbrt97.6%
cbrt-unprod97.6%
frac-times97.6%
metadata-eval97.6%
add-sqr-sqrt97.6%
inv-pow97.6%
sqrt-pow297.6%
metadata-eval97.6%
Applied egg-rr97.6%
Taylor expanded in c around 0 97.1%
neg-mul-197.1%
cancel-sign-sub-inv97.1%
metadata-eval97.1%
Simplified97.1%
Final simplification97.1%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* PI (* cosTheta (+ -1.0 (- (sqrt (/ 1.0 PI)) c)))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + (((float) M_PI) * (cosTheta * (-1.0f + (sqrtf((1.0f / ((float) M_PI))) - c)))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(pi) * Float32(cosTheta * Float32(Float32(-1.0) + Float32(sqrt(Float32(Float32(1.0) / Float32(pi))) - c)))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + (single(pi) * (cosTheta * (single(-1.0) + (sqrt((single(1.0) / single(pi))) - c))))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \pi \cdot \left(cosTheta \cdot \left(-1 + \left(\sqrt{\frac{1}{\pi}} - c\right)\right)\right)\right)
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
Taylor expanded in cosTheta around 0 95.7%
mul-1-neg95.7%
unsub-neg95.7%
associate-*r*95.7%
*-commutative95.7%
associate-*l*95.7%
mul-1-neg95.7%
unsub-neg95.7%
Simplified95.7%
Final simplification95.7%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* PI (* cosTheta (+ (pow PI -0.5) -1.0))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + (((float) M_PI) * (cosTheta * (powf(((float) M_PI), -0.5f) + -1.0f))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(pi) * Float32(cosTheta * Float32((Float32(pi) ^ Float32(-0.5)) + Float32(-1.0)))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + (single(pi) * (cosTheta * ((single(pi) ^ single(-0.5)) + single(-1.0))))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \pi \cdot \left(cosTheta \cdot \left({\pi}^{-0.5} + -1\right)\right)\right)
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
inv-pow98.2%
add-sqr-sqrt97.5%
unpow-prod-down97.4%
Applied egg-rr94.3%
pow-sqr94.5%
metadata-eval94.5%
Simplified94.5%
Taylor expanded in c around 0 94.4%
Taylor expanded in cosTheta around 0 95.5%
mul-1-neg95.5%
unsub-neg95.5%
associate-*r*95.5%
*-commutative95.5%
mul-1-neg95.5%
unsub-neg95.5%
Simplified95.5%
pow195.5%
associate-*l*95.5%
pow1/295.5%
inv-pow95.5%
pow-pow95.5%
metadata-eval95.5%
Applied egg-rr95.5%
unpow195.5%
Simplified95.5%
Final simplification95.5%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (sqrt PI)))
float code(float cosTheta, float c) {
return cosTheta * sqrtf(((float) M_PI));
}
function code(cosTheta, c) return Float32(cosTheta * sqrt(Float32(pi))) end
function tmp = code(cosTheta, c) tmp = cosTheta * sqrt(single(pi)); end
\begin{array}{l}
\\
cosTheta \cdot \sqrt{\pi}
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
Taylor expanded in cosTheta around 0 93.2%
Final simplification93.2%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 c))
float code(float cosTheta, float c) {
return 1.0f / c;
}
real(4) function code(costheta, c)
real(4), intent (in) :: costheta
real(4), intent (in) :: c
code = 1.0e0 / c
end function
function code(cosTheta, c) return Float32(Float32(1.0) / c) end
function tmp = code(cosTheta, c) tmp = single(1.0) / c; end
\begin{array}{l}
\\
\frac{1}{c}
\end{array}
Initial program 97.6%
associate-+l+97.6%
+-commutative97.6%
fma-define97.6%
Simplified98.2%
Taylor expanded in c around inf 5.0%
Final simplification5.0%
herbie shell --seed 2024100
(FPCore (cosTheta c)
:name "Beckmann Sample, normalization factor"
:precision binary32
:pre (and (and (< 0.0 cosTheta) (< cosTheta 0.9999)) (and (< -1.0 c) (< c 1.0)))
(/ 1.0 (+ (+ 1.0 c) (* (* (/ 1.0 (sqrt PI)) (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta)) (exp (* (- cosTheta) cosTheta))))))