
(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 13 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
(log1p
(expm1
(/
1.0
(fma
(/ (sqrt (- 1.0 (+ cosTheta cosTheta))) (* cosTheta (sqrt PI)))
(exp (- (pow cosTheta 2.0)))
(+ 1.0 c))))))
float code(float cosTheta, float c) {
return log1pf(expm1f((1.0f / fmaf((sqrtf((1.0f - (cosTheta + cosTheta))) / (cosTheta * sqrtf(((float) M_PI)))), expf(-powf(cosTheta, 2.0f)), (1.0f + c)))));
}
function code(cosTheta, c) return log1p(expm1(Float32(Float32(1.0) / fma(Float32(sqrt(Float32(Float32(1.0) - Float32(cosTheta + cosTheta))) / Float32(cosTheta * sqrt(Float32(pi)))), exp(Float32(-(cosTheta ^ Float32(2.0)))), Float32(Float32(1.0) + c))))) end
\begin{array}{l}
\\
\mathsf{log1p}\left(\mathsf{expm1}\left(\frac{1}{\mathsf{fma}\left(\frac{\sqrt{1 - \left(cosTheta + cosTheta\right)}}{cosTheta \cdot \sqrt{\pi}}, e^{-{cosTheta}^{2}}, 1 + c\right)}\right)\right)
\end{array}
Initial program 97.4%
add-cube-cbrt97.6%
pow397.6%
Applied egg-rr97.6%
Applied egg-rr98.5%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
(+ 1.0 c)
(*
(/ (sqrt (- 1.0 (+ cosTheta cosTheta))) (* cosTheta (sqrt PI)))
(exp (* cosTheta (- cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / ((1.0f + c) + ((sqrtf((1.0f - (cosTheta + cosTheta))) / (cosTheta * sqrtf(((float) M_PI)))) * expf((cosTheta * -cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(Float32(1.0) + c) + Float32(Float32(sqrt(Float32(Float32(1.0) - Float32(cosTheta + cosTheta))) / Float32(cosTheta * sqrt(Float32(pi)))) * 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 * sqrt(single(pi)))) * exp((cosTheta * -cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{\left(1 + c\right) + \frac{\sqrt{1 - \left(cosTheta + cosTheta\right)}}{cosTheta \cdot \sqrt{\pi}} \cdot e^{cosTheta \cdot \left(-cosTheta\right)}}
\end{array}
Initial program 97.4%
add-cube-cbrt97.6%
pow397.6%
Applied egg-rr97.6%
frac-times98.1%
*-un-lft-identity98.1%
associate--l-98.2%
rem-cube-cbrt98.5%
*-commutative98.5%
Applied egg-rr98.5%
Final simplification98.5%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(+
c
(*
(/ (exp (- (pow cosTheta 2.0))) cosTheta)
(sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI)))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + ((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(c + 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) + (c + ((exp(-(cosTheta ^ single(2.0))) / cosTheta) * sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi)))))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \frac{e^{-{cosTheta}^{2}}}{cosTheta} \cdot \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}}\right)}
\end{array}
Initial program 97.4%
+-commutative97.4%
fma-define97.4%
associate-*l/98.1%
*-lft-identity98.1%
associate--l-98.1%
sub-neg98.1%
neg-mul-198.1%
distribute-lft-out98.1%
distribute-rgt-out98.1%
metadata-eval98.1%
distribute-lft-neg-out98.1%
distribute-rgt-neg-out98.1%
exp-prod98.1%
Simplified98.1%
Taylor expanded in c around 0 97.6%
Final simplification97.6%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(*
(sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI))
(/ (exp (* cosTheta (- cosTheta))) cosTheta)))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (sqrtf(((1.0f + (cosTheta * -2.0f)) / ((float) M_PI))) * (expf((cosTheta * -cosTheta)) / cosTheta)));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(sqrt(Float32(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0))) / Float32(pi))) * Float32(exp(Float32(cosTheta * Float32(-cosTheta))) / cosTheta)))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi))) * (exp((cosTheta * -cosTheta)) / cosTheta))); end
\begin{array}{l}
\\
\frac{1}{1 + \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}} \cdot \frac{e^{cosTheta \cdot \left(-cosTheta\right)}}{cosTheta}}
\end{array}
Initial program 97.4%
add-cube-cbrt97.6%
pow397.6%
Applied egg-rr97.6%
Taylor expanded in c around 0 97.2%
neg-mul-197.2%
cancel-sign-sub-inv97.2%
metadata-eval97.2%
*-commutative97.2%
Simplified97.2%
unpow297.2%
distribute-lft-neg-out97.2%
Applied egg-rr97.2%
Final simplification97.2%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* (* cosTheta PI) (+ -1.0 (- (sqrt (/ 1.0 PI)) c))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + ((cosTheta * ((float) M_PI)) * (-1.0f + (sqrtf((1.0f / ((float) M_PI))) - c))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(cosTheta * Float32(pi)) * Float32(Float32(-1.0) + Float32(sqrt(Float32(Float32(1.0) / Float32(pi))) - c))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + ((cosTheta * single(pi)) * (single(-1.0) + (sqrt((single(1.0) / single(pi))) - c)))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \left(cosTheta \cdot \pi\right) \cdot \left(-1 + \left(\sqrt{\frac{1}{\pi}} - c\right)\right)\right)
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
Taylor expanded in cosTheta around 0 96.1%
mul-1-neg96.1%
unsub-neg96.1%
associate-*r*96.1%
mul-1-neg96.1%
unsub-neg96.1%
Simplified96.1%
Final simplification96.1%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* (* cosTheta PI) (+ -1.0 (sqrt (/ 1.0 PI)))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + ((cosTheta * ((float) M_PI)) * (-1.0f + sqrtf((1.0f / ((float) M_PI))))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(cosTheta * Float32(pi)) * Float32(Float32(-1.0) + sqrt(Float32(Float32(1.0) / Float32(pi))))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + ((cosTheta * single(pi)) * (single(-1.0) + sqrt((single(1.0) / single(pi)))))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \left(cosTheta \cdot \pi\right) \cdot \left(-1 + \sqrt{\frac{1}{\pi}}\right)\right)
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
inv-pow98.5%
add-sqr-sqrt97.7%
unpow-prod-down97.3%
Applied egg-rr94.4%
pow-sqr94.7%
+-commutative94.7%
fma-define94.7%
+-commutative94.7%
associate-+l+94.7%
fma-define94.7%
metadata-eval94.7%
Simplified94.7%
Taylor expanded in c around 0 94.7%
Taylor expanded in cosTheta around 0 96.0%
mul-1-neg96.0%
unsub-neg96.0%
associate-*r*96.0%
mul-1-neg96.0%
unsub-neg96.0%
Simplified96.0%
Final simplification96.0%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (/ (sqrt (/ (fma cosTheta -2.0 1.0) PI)) cosTheta))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (sqrtf((fmaf(cosTheta, -2.0f, 1.0f) / ((float) M_PI))) / cosTheta));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(sqrt(Float32(fma(cosTheta, Float32(-2.0), Float32(1.0)) / Float32(pi))) / cosTheta))) end
\begin{array}{l}
\\
\frac{1}{1 + \frac{\sqrt{\frac{\mathsf{fma}\left(cosTheta, -2, 1\right)}{\pi}}}{cosTheta}}
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
inv-pow98.5%
add-sqr-sqrt97.7%
unpow-prod-down97.3%
Applied egg-rr94.4%
pow-sqr94.7%
+-commutative94.7%
fma-define94.7%
+-commutative94.7%
associate-+l+94.7%
fma-define94.7%
metadata-eval94.7%
Simplified94.7%
Taylor expanded in c around 0 94.7%
Taylor expanded in cosTheta around 0 94.9%
associate-*l/95.3%
*-un-lft-identity95.3%
+-commutative95.3%
*-commutative95.3%
fma-define95.3%
Applied egg-rr95.3%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(*
(/ 1.0 cosTheta)
(sqrt (* cosTheta (- (/ 1.0 (* cosTheta PI)) (/ 2.0 PI))))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + ((1.0f / cosTheta) * sqrtf((cosTheta * ((1.0f / (cosTheta * ((float) M_PI))) - (2.0f / ((float) M_PI)))))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(Float32(1.0) / cosTheta) * sqrt(Float32(cosTheta * Float32(Float32(Float32(1.0) / Float32(cosTheta * Float32(pi))) - Float32(Float32(2.0) / Float32(pi)))))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + ((single(1.0) / cosTheta) * sqrt((cosTheta * ((single(1.0) / (cosTheta * single(pi))) - (single(2.0) / single(pi))))))); end
\begin{array}{l}
\\
\frac{1}{1 + \frac{1}{cosTheta} \cdot \sqrt{cosTheta \cdot \left(\frac{1}{cosTheta \cdot \pi} - \frac{2}{\pi}\right)}}
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
inv-pow98.5%
add-sqr-sqrt97.7%
unpow-prod-down97.3%
Applied egg-rr94.4%
pow-sqr94.7%
+-commutative94.7%
fma-define94.7%
+-commutative94.7%
associate-+l+94.7%
fma-define94.7%
metadata-eval94.7%
Simplified94.7%
Taylor expanded in c around 0 94.7%
Taylor expanded in cosTheta around 0 94.9%
Taylor expanded in cosTheta around inf 94.9%
associate-*r/94.9%
metadata-eval94.9%
Simplified94.9%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (* (/ 1.0 cosTheta) (sqrt (+ (/ 1.0 PI) (* -2.0 (/ cosTheta PI))))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + ((1.0f / cosTheta) * sqrtf(((1.0f / ((float) M_PI)) + (-2.0f * (cosTheta / ((float) M_PI)))))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(Float32(1.0) / cosTheta) * sqrt(Float32(Float32(Float32(1.0) / Float32(pi)) + Float32(Float32(-2.0) * Float32(cosTheta / Float32(pi)))))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + ((single(1.0) / cosTheta) * sqrt(((single(1.0) / single(pi)) + (single(-2.0) * (cosTheta / single(pi))))))); end
\begin{array}{l}
\\
\frac{1}{1 + \frac{1}{cosTheta} \cdot \sqrt{\frac{1}{\pi} + -2 \cdot \frac{cosTheta}{\pi}}}
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
inv-pow98.5%
add-sqr-sqrt97.7%
unpow-prod-down97.3%
Applied egg-rr94.4%
pow-sqr94.7%
+-commutative94.7%
fma-define94.7%
+-commutative94.7%
associate-+l+94.7%
fma-define94.7%
metadata-eval94.7%
Simplified94.7%
Taylor expanded in c around 0 94.7%
Taylor expanded in cosTheta around 0 94.9%
Taylor expanded in cosTheta around 0 94.9%
Final simplification94.9%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (* (sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI)) (/ 1.0 cosTheta)))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (sqrtf(((1.0f + (cosTheta * -2.0f)) / ((float) M_PI))) * (1.0f / cosTheta)));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(sqrt(Float32(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0))) / Float32(pi))) * Float32(Float32(1.0) / cosTheta)))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi))) * (single(1.0) / cosTheta))); end
\begin{array}{l}
\\
\frac{1}{1 + \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}} \cdot \frac{1}{cosTheta}}
\end{array}
Initial program 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
inv-pow98.5%
add-sqr-sqrt97.7%
unpow-prod-down97.3%
Applied egg-rr94.4%
pow-sqr94.7%
+-commutative94.7%
fma-define94.7%
+-commutative94.7%
associate-+l+94.7%
fma-define94.7%
metadata-eval94.7%
Simplified94.7%
Taylor expanded in c around 0 94.7%
Taylor expanded in cosTheta around 0 94.9%
Final simplification94.9%
(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 97.4%
frac-times98.5%
*-un-lft-identity98.5%
sub-neg98.5%
sub-neg98.5%
add-sqr-sqrt-0.0%
sqrt-unprod91.7%
sqr-neg91.7%
sqrt-unprod91.7%
add-sqr-sqrt91.7%
add-sqr-sqrt-0.0%
sqrt-unprod91.1%
sqr-neg91.1%
sqrt-unprod91.1%
add-sqr-sqrt91.1%
Applied egg-rr91.1%
Taylor expanded in cosTheta around 0 92.3%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 c)))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + c);
}
real(4) function code(costheta, c)
real(4), intent (in) :: costheta
real(4), intent (in) :: c
code = 1.0e0 / (1.0e0 + c)
end function
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + c)) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + c); end
\begin{array}{l}
\\
\frac{1}{1 + c}
\end{array}
Initial program 97.4%
add-cube-cbrt97.6%
pow397.6%
Applied egg-rr97.6%
Taylor expanded in cosTheta around 0 90.8%
associate-*l/91.2%
*-lft-identity91.2%
Simplified91.2%
Taylor expanded in cosTheta around inf 10.9%
(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 97.4%
associate-+l+97.4%
+-commutative97.4%
fma-define97.4%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.5%
sub-neg98.5%
neg-mul-198.5%
distribute-lft-out98.5%
distribute-rgt-out98.5%
metadata-eval98.5%
exp-prod98.5%
Simplified98.5%
Taylor expanded in c around inf 5.1%
herbie shell --seed 2024135
(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))))))