
(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 (/ 1.0 (fma (/ (/ (sqrt (+ 1.0 (* cosTheta -2.0))) cosTheta) (sqrt PI)) (pow (exp cosTheta) (- cosTheta)) (+ 1.0 c))))
float code(float cosTheta, float c) {
return 1.0f / fmaf(((sqrtf((1.0f + (cosTheta * -2.0f))) / cosTheta) / sqrtf(((float) M_PI))), powf(expf(cosTheta), -cosTheta), (1.0f + c));
}
function code(cosTheta, c) return Float32(Float32(1.0) / fma(Float32(Float32(sqrt(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0)))) / cosTheta) / sqrt(Float32(pi))), (exp(cosTheta) ^ Float32(-cosTheta)), Float32(Float32(1.0) + c))) end
\begin{array}{l}
\\
\frac{1}{\mathsf{fma}\left(\frac{\frac{\sqrt{1 + cosTheta \cdot -2}}{cosTheta}}{\sqrt{\pi}}, {\left(e^{cosTheta}\right)}^{\left(-cosTheta\right)}, 1 + c\right)}
\end{array}
Initial program 97.7%
+-commutative97.7%
fma-define97.7%
associate-*l/98.4%
*-lft-identity98.4%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
distribute-lft-neg-out98.4%
distribute-rgt-neg-out98.4%
exp-prod98.4%
Simplified98.4%
(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(Float32(sqrt(Float32(Float32(1.0) - Float32(cosTheta + cosTheta))) / cosTheta) / sqrt(Float32(pi))) * exp(Float32(-Float32(cosTheta * 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{\frac{\sqrt{1 - \left(cosTheta + cosTheta\right)}}{cosTheta}}{\sqrt{\pi}} \cdot e^{-cosTheta \cdot cosTheta}}
\end{array}
Initial program 97.7%
add-cube-cbrt97.9%
pow397.9%
Applied egg-rr97.9%
associate-*l/98.1%
*-un-lft-identity98.1%
associate--l-98.1%
rem-cube-cbrt98.4%
Applied egg-rr98.4%
Final simplification98.4%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(*
(/ (/ (sqrt (- 1.0 (+ cosTheta cosTheta))) cosTheta) (sqrt PI))
(exp (- (* cosTheta cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (((sqrtf((1.0f - (cosTheta + cosTheta))) / cosTheta) / sqrtf(((float) M_PI))) * expf(-(cosTheta * cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(Float32(sqrt(Float32(Float32(1.0) - Float32(cosTheta + cosTheta))) / cosTheta) / sqrt(Float32(pi))) * exp(Float32(-Float32(cosTheta * cosTheta)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (((sqrt((single(1.0) - (cosTheta + cosTheta))) / cosTheta) / sqrt(single(pi))) * exp(-(cosTheta * cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{1 + \frac{\frac{\sqrt{1 - \left(cosTheta + cosTheta\right)}}{cosTheta}}{\sqrt{\pi}} \cdot e^{-cosTheta \cdot cosTheta}}
\end{array}
Initial program 97.7%
add-cube-cbrt97.9%
pow397.9%
Applied egg-rr97.9%
associate-*l/98.1%
*-un-lft-identity98.1%
associate--l-98.1%
rem-cube-cbrt98.4%
Applied egg-rr98.4%
Taylor expanded in c around 0 98.2%
Final simplification98.2%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(+
c
(*
(/ (exp (- (* cosTheta cosTheta))) cosTheta)
(sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI)))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + ((expf(-(cosTheta * cosTheta)) / 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(-Float32(cosTheta * cosTheta))) / 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 * cosTheta)) / cosTheta) * sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi)))))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \frac{e^{-cosTheta \cdot cosTheta}}{cosTheta} \cdot \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}}\right)}
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in c around 0 97.9%
unpow297.9%
Applied egg-rr97.9%
Final simplification97.9%
(FPCore (cosTheta c)
:precision binary32
(/
1.0
(+
1.0
(+
c
(*
(sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI))
(/ (- 1.0 (pow cosTheta 2.0)) cosTheta))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + (sqrtf(((1.0f + (cosTheta * -2.0f)) / ((float) M_PI))) * ((1.0f - powf(cosTheta, 2.0f)) / cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(c + Float32(sqrt(Float32(Float32(Float32(1.0) + Float32(cosTheta * Float32(-2.0))) / Float32(pi))) * Float32(Float32(Float32(1.0) - (cosTheta ^ Float32(2.0))) / cosTheta))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (c + (sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi))) * ((single(1.0) - (cosTheta ^ single(2.0))) / cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}} \cdot \frac{1 - {cosTheta}^{2}}{cosTheta}\right)}
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in c around 0 97.9%
Taylor expanded in cosTheta around 0 96.8%
neg-mul-196.8%
unsub-neg96.8%
Simplified96.8%
Final simplification96.8%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (+ (sqrt PI) (* (* cosTheta PI) (+ -1.0 (- (pow PI -0.5) c))))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) + ((cosTheta * ((float) M_PI)) * (-1.0f + (powf(((float) M_PI), -0.5f) - c))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) + Float32(Float32(cosTheta * Float32(pi)) * Float32(Float32(-1.0) + Float32((Float32(pi) ^ Float32(-0.5)) - c))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) + ((cosTheta * single(pi)) * (single(-1.0) + ((single(pi) ^ single(-0.5)) - c)))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} + \left(cosTheta \cdot \pi\right) \cdot \left(-1 + \left({\pi}^{-0.5} - c\right)\right)\right)
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 96.4%
mul-1-neg96.4%
unsub-neg96.4%
associate-*r*96.4%
associate-+r+96.4%
mul-1-neg96.4%
unsub-neg96.4%
Simplified96.4%
sqrt-div96.4%
metadata-eval96.4%
associate--l+96.4%
pow1/296.4%
pow-flip96.4%
metadata-eval96.4%
Applied egg-rr96.4%
Final simplification96.4%
(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 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 96.4%
mul-1-neg96.4%
unsub-neg96.4%
associate-*r*96.4%
associate-+r+96.4%
mul-1-neg96.4%
unsub-neg96.4%
Simplified96.4%
Taylor expanded in c around 0 96.2%
Final simplification96.2%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (+ c (* (sqrt (/ (+ 1.0 (* cosTheta -2.0)) PI)) (/ 1.0 cosTheta))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + (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(c + 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) + (c + (sqrt(((single(1.0) + (cosTheta * single(-2.0))) / single(pi))) * (single(1.0) / cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \sqrt{\frac{1 + cosTheta \cdot -2}{\pi}} \cdot \frac{1}{cosTheta}\right)}
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in c around 0 97.9%
Taylor expanded in cosTheta around 0 95.6%
Final simplification95.6%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (+ c (* (/ 1.0 (sqrt PI)) (+ -1.0 (/ 1.0 cosTheta)))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + (c + ((1.0f / sqrtf(((float) M_PI))) * (-1.0f + (1.0f / cosTheta)))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(c + Float32(Float32(Float32(1.0) / sqrt(Float32(pi))) * Float32(Float32(-1.0) + Float32(Float32(1.0) / cosTheta)))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + (c + ((single(1.0) / sqrt(single(pi))) * (single(-1.0) + (single(1.0) / cosTheta))))); end
\begin{array}{l}
\\
\frac{1}{1 + \left(c + \frac{1}{\sqrt{\pi}} \cdot \left(-1 + \frac{1}{cosTheta}\right)\right)}
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 95.4%
mul-1-neg95.4%
Simplified95.4%
Taylor expanded in cosTheta around inf 95.4%
associate--l+95.4%
associate--l+95.4%
sub-neg95.4%
mul-1-neg95.4%
+-commutative95.4%
distribute-rgt-out95.4%
unpow1/295.4%
rem-exp-log95.4%
rec-exp95.4%
exp-prod95.4%
distribute-lft-neg-out95.4%
rec-exp95.4%
exp-to-pow95.4%
unpow1/295.4%
Simplified95.4%
(FPCore (cosTheta c) :precision binary32 (/ 1.0 (+ 1.0 (* (/ 1.0 (sqrt PI)) (+ -1.0 (/ 1.0 cosTheta))))))
float code(float cosTheta, float c) {
return 1.0f / (1.0f + ((1.0f / sqrtf(((float) M_PI))) * (-1.0f + (1.0f / cosTheta))));
}
function code(cosTheta, c) return Float32(Float32(1.0) / Float32(Float32(1.0) + Float32(Float32(Float32(1.0) / sqrt(Float32(pi))) * Float32(Float32(-1.0) + Float32(Float32(1.0) / cosTheta))))) end
function tmp = code(cosTheta, c) tmp = single(1.0) / (single(1.0) + ((single(1.0) / sqrt(single(pi))) * (single(-1.0) + (single(1.0) / cosTheta)))); end
\begin{array}{l}
\\
\frac{1}{1 + \frac{1}{\sqrt{\pi}} \cdot \left(-1 + \frac{1}{cosTheta}\right)}
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 95.4%
mul-1-neg95.4%
Simplified95.4%
Taylor expanded in c around 0 95.2%
associate--l+95.2%
sub-neg95.2%
mul-1-neg95.2%
+-commutative95.2%
distribute-rgt-out95.2%
unpow1/295.2%
rem-exp-log95.2%
rec-exp95.2%
exp-prod95.2%
distribute-lft-neg-out95.2%
rec-exp95.2%
exp-to-pow95.2%
unpow1/295.2%
Simplified95.2%
(FPCore (cosTheta c) :precision binary32 (* cosTheta (- (sqrt PI) (* c (* cosTheta PI)))))
float code(float cosTheta, float c) {
return cosTheta * (sqrtf(((float) M_PI)) - (c * (cosTheta * ((float) M_PI))));
}
function code(cosTheta, c) return Float32(cosTheta * Float32(sqrt(Float32(pi)) - Float32(c * Float32(cosTheta * Float32(pi))))) end
function tmp = code(cosTheta, c) tmp = cosTheta * (sqrt(single(pi)) - (c * (cosTheta * single(pi)))); end
\begin{array}{l}
\\
cosTheta \cdot \left(\sqrt{\pi} - c \cdot \left(cosTheta \cdot \pi\right)\right)
\end{array}
Initial program 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 96.4%
mul-1-neg96.4%
unsub-neg96.4%
associate-*r*96.4%
associate-+r+96.4%
mul-1-neg96.4%
unsub-neg96.4%
Simplified96.4%
Taylor expanded in c around inf 93.6%
Final simplification93.6%
(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 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in cosTheta around 0 95.4%
mul-1-neg95.4%
Simplified95.4%
Taylor expanded in cosTheta around 0 93.6%
(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 97.7%
associate-+l+97.7%
+-commutative97.7%
fma-define97.7%
times-frac98.5%
*-lft-identity98.5%
associate--l-98.4%
sub-neg98.4%
neg-mul-198.4%
distribute-lft-out98.4%
distribute-rgt-out98.4%
metadata-eval98.4%
exp-prod98.4%
Simplified98.4%
Taylor expanded in c around inf 10.5%
Taylor expanded in c around 0 10.5%
herbie shell --seed 2024141
(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))))))