
(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 8 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 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
times-frac98.7%
*-lft-identity98.7%
associate--l-98.7%
sub-neg98.7%
neg-mul-198.7%
distribute-lft-out98.7%
distribute-rgt-out98.7%
metadata-eval98.7%
exp-prod98.7%
Simplified98.7%
Final simplification98.7%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(/ (/ 1.0 (sqrt (/ PI (- 1.0 (* cosTheta 2.0))))) cosTheta)
(exp (* cosTheta (- cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (((1.0f / sqrtf((((float) M_PI) / (1.0f - (cosTheta * 2.0f))))) / 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(Float32(pi) / Float32(Float32(1.0) - Float32(cosTheta * Float32(2.0)))))) / cosTheta) * exp(Float32(cosTheta * Float32(-cosTheta)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (((single(1.0) / sqrt((single(pi) / (single(1.0) - (cosTheta * single(2.0)))))) / cosTheta) * exp((cosTheta * -cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \frac{\frac{1}{\sqrt{\frac{\pi}{1 - cosTheta \cdot 2}}}}{cosTheta} \cdot e^{cosTheta \cdot \left(-cosTheta\right)}}
\end{array}
Initial program 97.8%
*-un-lft-identity97.8%
pow1/297.8%
pow-flip97.8%
metadata-eval97.8%
Applied egg-rr97.8%
*-lft-identity97.8%
Simplified97.8%
associate-*r/98.1%
associate--l-98.1%
Applied egg-rr98.1%
*-commutative98.1%
count-298.1%
add-sqr-sqrt98.1%
sqrt-unprod98.1%
pow-prod-up98.1%
metadata-eval98.1%
inv-pow98.1%
sqrt-prod98.2%
div-inv98.2%
clear-num98.2%
sqrt-div98.2%
metadata-eval98.2%
*-commutative98.2%
Applied egg-rr98.2%
Final simplification98.2%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(exp (* cosTheta (- cosTheta)))
(/ (sqrt (/ (- 1.0 (* cosTheta 2.0)) PI)) cosTheta)))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (expf((cosTheta * -cosTheta)) * (sqrtf(((1.0f - (cosTheta * 2.0f)) / ((float) M_PI))) / cosTheta)));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(exp(Float32(cosTheta * Float32(-cosTheta))) * Float32(sqrt(Float32(Float32(Float32(1.0) - Float32(cosTheta * Float32(2.0))) / Float32(pi))) / cosTheta)))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (exp((cosTheta * -cosTheta)) * (sqrt(((single(1.0) - (cosTheta * single(2.0))) / single(pi))) / cosTheta))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + e^{cosTheta \cdot \left(-cosTheta\right)} \cdot \frac{\sqrt{\frac{1 - cosTheta \cdot 2}{\pi}}}{cosTheta}}
\end{array}
Initial program 97.8%
*-un-lft-identity97.8%
pow1/297.8%
pow-flip97.8%
metadata-eval97.8%
Applied egg-rr97.8%
*-lft-identity97.8%
Simplified97.8%
associate-*r/98.1%
associate--l-98.1%
Applied egg-rr98.1%
*-commutative98.1%
count-298.1%
add-sqr-sqrt98.1%
sqrt-unprod98.1%
pow-prod-up98.1%
metadata-eval98.1%
inv-pow98.1%
sqrt-prod98.2%
div-inv98.2%
*-commutative98.2%
Applied egg-rr98.2%
Final simplification98.2%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* PI (* cosTheta (- (sqrt (/ 1.0 PI)) (+ 1.0 c)))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + (((float) M_PI) * (cosTheta * (sqrtf((1.0f / ((float) M_PI))) - (1.0f + c)))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(pi) * Float32(cosTheta * Float32(sqrt(Float32(Float32(1.0) / Float32(pi))) - Float32(Float32(1.0) + c)))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + (single(pi) * (cosTheta * (sqrt((single(1.0) / single(pi))) - (single(1.0) + c))))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \pi \cdot \left(cosTheta \cdot \left(\sqrt{\frac{1}{\pi}} - \left(1 + c\right)\right)\right)\right)
\end{array}
Initial program 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
times-frac98.7%
*-lft-identity98.7%
associate--l-98.7%
sub-neg98.7%
neg-mul-198.7%
distribute-lft-out98.7%
distribute-rgt-out98.7%
metadata-eval98.7%
exp-prod98.7%
Simplified98.7%
Taylor expanded in cosTheta around 0 95.2%
mul-1-neg95.2%
unsub-neg95.2%
associate-*r*95.2%
*-commutative95.2%
associate-*l*95.2%
associate-+r+95.2%
mul-1-neg95.2%
unsub-neg95.2%
Simplified95.2%
Final simplification95.2%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* (* cosTheta PI) (+ (sqrt (/ 1.0 PI)) -1.0)))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + ((cosTheta * ((float) M_PI)) * (sqrtf((1.0f / ((float) M_PI))) + -1.0f)));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(cosTheta * Float32(pi)) * Float32(sqrt(Float32(Float32(1.0) / Float32(pi))) + Float32(-1.0))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + ((cosTheta * single(pi)) * (sqrt((single(1.0) / single(pi))) + single(-1.0)))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \left(cosTheta \cdot \pi\right) \cdot \left(\sqrt{\frac{1}{\pi}} + -1\right)\right)
\end{array}
Initial program 97.8%
Taylor expanded in c around 0 97.8%
Taylor expanded in cosTheta around 0 95.1%
mul-1-neg95.1%
unsub-neg95.1%
associate-*r*95.1%
mul-1-neg95.1%
unsub-neg95.1%
Simplified95.1%
Final simplification95.1%
(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 97.8%
*-un-lft-identity97.8%
pow1/297.8%
pow-flip97.8%
metadata-eval97.8%
Applied egg-rr97.8%
*-lft-identity97.8%
Simplified97.8%
associate-*r/98.1%
associate--l-98.1%
Applied egg-rr98.1%
Taylor expanded in cosTheta around 0 93.1%
(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}
\\
1 - c
\end{array}
Initial program 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
times-frac98.7%
*-lft-identity98.7%
associate--l-98.7%
sub-neg98.7%
neg-mul-198.7%
distribute-lft-out98.7%
distribute-rgt-out98.7%
metadata-eval98.7%
exp-prod98.7%
Simplified98.7%
Taylor expanded in c around inf 10.6%
Taylor expanded in c around 0 10.6%
mul-1-neg10.6%
unsub-neg10.6%
Simplified10.6%
(FPCore (cosTheta c) :precision binary32 1.0)
float code(float cosTheta, float c) {
return 1.0f;
}
real(4) function code(costheta, c)
real(4), intent (in) :: costheta
real(4), intent (in) :: c
code = 1.0e0
end function
function code(cosTheta, c) return Float32(1.0) end
function tmp = code(cosTheta, c) tmp = single(1.0); end
\begin{array}{l}
\\
1
\end{array}
Initial program 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
times-frac98.7%
*-lft-identity98.7%
associate--l-98.7%
sub-neg98.7%
neg-mul-198.7%
distribute-lft-out98.7%
distribute-rgt-out98.7%
metadata-eval98.7%
exp-prod98.7%
Simplified98.7%
Taylor expanded in c around inf 10.6%
Taylor expanded in c around 0 10.6%
herbie shell --seed 2024085
(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))))))