
(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 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
Simplified98.4%
Final simplification98.4%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(*
(/ (pow PI -0.16666666666666666) (cbrt PI))
(/ (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), -0.16666666666666666f) / cbrtf(((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(pi) ^ Float32(-0.16666666666666666)) / cbrt(Float32(pi))) * Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta)) * exp(Float32(cosTheta * Float32(-cosTheta)))))) end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{{\pi}^{-0.16666666666666666}}{\sqrt[3]{\pi}} \cdot \frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta}\right) \cdot e^{cosTheta \cdot \left(-cosTheta\right)}}
\end{array}
Initial program 97.8%
*-un-lft-identity97.8%
inv-pow97.8%
sqrt-pow297.8%
metadata-eval97.8%
Applied egg-rr97.8%
*-lft-identity97.8%
Simplified97.8%
add-cube-cbrt97.8%
cbrt-prod97.8%
pow-prod-up98.1%
metadata-eval98.1%
inv-pow98.1%
*-commutative98.1%
pow1/398.1%
pow-pow98.1%
metadata-eval98.1%
cbrt-div98.1%
metadata-eval98.1%
Applied egg-rr98.1%
associate-*r/98.1%
*-rgt-identity98.1%
Simplified98.1%
Final simplification98.1%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(exp (* cosTheta (- cosTheta)))
(* (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta) (pow PI -0.5))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (expf((cosTheta * -cosTheta)) * ((sqrtf(((1.0f - cosTheta) - cosTheta)) / cosTheta) * powf(((float) M_PI), -0.5f))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(exp(Float32(cosTheta * Float32(-cosTheta))) * Float32(Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta) * (Float32(pi) ^ Float32(-0.5)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (exp((cosTheta * -cosTheta)) * ((sqrt(((single(1.0) - cosTheta) - cosTheta)) / cosTheta) * (single(pi) ^ single(-0.5))))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + e^{cosTheta \cdot \left(-cosTheta\right)} \cdot \left(\frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta} \cdot {\pi}^{-0.5}\right)}
\end{array}
Initial program 97.8%
*-un-lft-identity97.8%
inv-pow97.8%
sqrt-pow297.8%
metadata-eval97.8%
Applied egg-rr97.8%
*-lft-identity97.8%
Simplified97.8%
Final simplification97.8%
(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 97.8%
add-cube-cbrt97.8%
cbrt-unprod97.8%
frac-times98.1%
metadata-eval98.1%
add-sqr-sqrt98.1%
inv-pow98.1%
sqrt-pow298.1%
metadata-eval98.1%
Applied egg-rr98.1%
Taylor expanded in c around 0 97.7%
neg-mul-197.7%
cancel-sign-sub-inv97.7%
metadata-eval97.7%
Simplified97.7%
Final simplification97.7%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* PI (* cosTheta (- -1.0 (- c (sqrt (/ 1.0 PI)))))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + (((float) M_PI) * (cosTheta * (-1.0f - (c - sqrtf((1.0f / ((float) M_PI))))))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(pi) * Float32(cosTheta * Float32(Float32(-1.0) - Float32(c - sqrt(Float32(Float32(1.0) / Float32(pi))))))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + (single(pi) * (cosTheta * (single(-1.0) - (c - sqrt((single(1.0) / single(pi)))))))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \pi \cdot \left(cosTheta \cdot \left(-1 - \left(c - \sqrt{\frac{1}{\pi}}\right)\right)\right)\right)
\end{array}
Initial program 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
Simplified98.4%
Taylor expanded in cosTheta around 0 96.6%
mul-1-neg96.6%
unsub-neg96.6%
*-commutative96.6%
associate-*l*96.6%
mul-1-neg96.6%
unsub-neg96.6%
Simplified96.6%
Final simplification96.6%
(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%
+-commutative97.8%
fma-define97.7%
associate-*l/98.3%
*-lft-identity98.3%
sub-neg98.3%
associate--l+98.3%
unsub-neg98.3%
neg-mul-198.3%
neg-mul-198.3%
distribute-rgt-out98.3%
metadata-eval98.3%
*-commutative98.3%
exp-prod98.3%
Simplified98.3%
add-sqr-sqrt97.6%
pow297.6%
Applied egg-rr95.7%
Taylor expanded in c around 0 95.7%
Taylor expanded in cosTheta around 0 96.5%
mul-1-neg96.5%
unsub-neg96.5%
associate-*r*96.5%
mul-1-neg96.5%
unsub-neg96.5%
Simplified96.5%
Final simplification96.5%
(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 97.8%
associate-+l+97.8%
+-commutative97.8%
fma-define97.8%
Simplified98.4%
associate-/l/98.3%
div-inv98.3%
*-un-lft-identity98.3%
times-frac98.3%
+-commutative98.3%
fma-define98.3%
Applied egg-rr98.3%
Taylor expanded in cosTheta around 0 94.3%
Final simplification94.3%
(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%
+-commutative97.8%
fma-define97.7%
associate-*l/98.3%
*-lft-identity98.3%
sub-neg98.3%
associate--l+98.3%
unsub-neg98.3%
neg-mul-198.3%
neg-mul-198.3%
distribute-rgt-out98.3%
metadata-eval98.3%
*-commutative98.3%
exp-prod98.3%
Simplified98.3%
add-sqr-sqrt97.6%
pow297.6%
Applied egg-rr95.7%
Taylor expanded in cosTheta around 0 93.2%
Taylor expanded in cosTheta around inf 10.4%
Taylor expanded in c around 0 10.4%
mul-1-neg10.4%
unsub-neg10.4%
Simplified10.4%
Final simplification10.4%
(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%
+-commutative97.8%
fma-define97.7%
associate-*l/98.3%
*-lft-identity98.3%
sub-neg98.3%
associate--l+98.3%
unsub-neg98.3%
neg-mul-198.3%
neg-mul-198.3%
distribute-rgt-out98.3%
metadata-eval98.3%
*-commutative98.3%
exp-prod98.3%
Simplified98.3%
add-sqr-sqrt97.6%
pow297.6%
Applied egg-rr95.7%
Taylor expanded in cosTheta around 0 93.2%
Taylor expanded in cosTheta around inf 10.4%
Taylor expanded in c around 0 10.4%
Final simplification10.4%
herbie shell --seed 2024095
(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))))))