
(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-def97.8%
times-frac98.6%
*-lft-identity98.6%
associate--l-98.6%
count-298.6%
*-commutative98.6%
exp-prod98.6%
Simplified98.6%
Final simplification98.6%
(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(1.0) / sqrt(Float32(pi))) * Float32(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(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) + \frac{1}{\sqrt{\pi}} \cdot \left(\frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta} \cdot e^{cosTheta \cdot \left(-cosTheta\right)}\right)}
\end{array}
Initial program 97.8%
associate-*l*97.8%
distribute-lft-neg-out97.8%
Simplified97.8%
Final simplification97.8%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(* (/ (sqrt (- (- 1.0 cosTheta) cosTheta)) cosTheta) (pow PI -0.5))
(exp (* cosTheta (- cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (((sqrtf(((1.0f - cosTheta) - cosTheta)) / cosTheta) * powf(((float) M_PI), -0.5f)) * expf((cosTheta * -cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(Float32(Float32(sqrt(Float32(Float32(Float32(1.0) - cosTheta) - cosTheta)) / cosTheta) * (Float32(pi) ^ Float32(-0.5))) * exp(Float32(cosTheta * Float32(-cosTheta)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (((sqrt(((single(1.0) - cosTheta) - cosTheta)) / cosTheta) * (single(pi) ^ single(-0.5))) * exp((cosTheta * -cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \left(\frac{\sqrt{\left(1 - cosTheta\right) - cosTheta}}{cosTheta} \cdot {\pi}^{-0.5}\right) \cdot e^{cosTheta \cdot \left(-cosTheta\right)}}
\end{array}
Initial program 97.8%
div-inv97.8%
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%
associate-*l*97.8%
distribute-lft-neg-out97.8%
Simplified97.8%
Taylor expanded in c around 0 97.8%
Final simplification97.8%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(exp (* cosTheta (- cosTheta)))
(* (pow PI -0.5) (+ (/ 1.0 cosTheta) -1.0))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + (expf((cosTheta * -cosTheta)) * (powf(((float) M_PI), -0.5f) * ((1.0f / cosTheta) + -1.0f))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(exp(Float32(cosTheta * Float32(-cosTheta))) * Float32((Float32(pi) ^ Float32(-0.5)) * Float32(Float32(Float32(1.0) / cosTheta) + Float32(-1.0)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / ((single(1.0) + c) + (exp((cosTheta * -cosTheta)) * ((single(pi) ^ single(-0.5)) * ((single(1.0) / cosTheta) + single(-1.0))))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + e^{cosTheta \cdot \left(-cosTheta\right)} \cdot \left({\pi}^{-0.5} \cdot \left(\frac{1}{cosTheta} + -1\right)\right)}
\end{array}
Initial program 97.8%
add-cube-cbrt97.8%
*-commutative97.8%
inv-pow97.8%
sqrt-pow297.8%
metadata-eval97.8%
cbrt-unprod97.8%
frac-times98.2%
metadata-eval98.2%
add-sqr-sqrt98.2%
Applied egg-rr98.2%
add-sqr-sqrt98.2%
sqrt-unprod98.2%
add-cbrt-cube98.2%
swap-sqr98.2%
add-cube-cbrt98.2%
add-cube-cbrt98.2%
pow-sqr98.2%
metadata-eval98.2%
inv-pow98.2%
pow1/398.2%
sqrt-pow198.2%
metadata-eval98.2%
Applied egg-rr98.2%
Taylor expanded in cosTheta around 0 96.3%
sub-neg96.3%
distribute-lft-in96.3%
Applied egg-rr96.1%
distribute-lft-in96.1%
Simplified96.1%
Final simplification96.1%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (+ c (* (+ (/ 1.0 cosTheta) -1.0) (sqrt (/ 1.0 PI)))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + (((1.0f / cosTheta) + -1.0f) * sqrtf((1.0f / ((float) M_PI))))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(c + Float32(Float32(Float32(Float32(1.0) / cosTheta) + Float32(-1.0)) * sqrt(Float32(Float32(1.0) / Float32(pi))))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (c + (((single(1.0) / cosTheta) + single(-1.0)) * sqrt((single(1.0) / single(pi)))))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \left(\frac{1}{cosTheta} + -1\right) \cdot \sqrt{\frac{1}{\pi}}\right)}
\end{array}
Initial program 97.8%
+-commutative97.8%
fma-def97.9%
associate-*l/98.4%
*-lft-identity98.4%
sub-neg98.4%
sub-neg98.4%
associate-+l+98.3%
count-298.3%
*-commutative98.3%
distribute-lft-neg-in98.3%
distribute-rgt-neg-in98.3%
metadata-eval98.3%
exp-prod98.3%
Simplified98.3%
Taylor expanded in cosTheta around 0 97.2%
Taylor expanded in cosTheta around 0 95.8%
+-commutative95.8%
distribute-rgt-out95.8%
+-commutative95.8%
Simplified95.8%
Final simplification95.8%
(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%
add-cube-cbrt97.8%
*-commutative97.8%
inv-pow97.8%
sqrt-pow297.8%
metadata-eval97.8%
cbrt-unprod97.8%
frac-times98.2%
metadata-eval98.2%
add-sqr-sqrt98.2%
Applied egg-rr98.2%
Taylor expanded in cosTheta around 0 93.7%
Final simplification93.7%
(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-def97.8%
times-frac98.6%
*-lft-identity98.6%
associate--l-98.6%
count-298.6%
*-commutative98.6%
exp-prod98.6%
Simplified98.6%
Taylor expanded in cosTheta around inf 10.5%
Taylor expanded in c around 0 10.5%
mul-1-neg10.5%
sub-neg10.5%
Simplified10.5%
Final simplification10.5%
(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-def97.8%
times-frac98.6%
*-lft-identity98.6%
associate--l-98.6%
count-298.6%
*-commutative98.6%
exp-prod98.6%
Simplified98.6%
Taylor expanded in cosTheta around inf 10.5%
Taylor expanded in c around 0 10.5%
Final simplification10.5%
herbie shell --seed 2023326
(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))))))