
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
:precision binary32
(exp
(+
(+
(-
(- (/ (* cosTheta_i cosTheta_O) v) (/ (* sinTheta_i sinTheta_O) v))
(/ 1.0 v))
0.6931)
(log (/ 1.0 (* 2.0 v))))))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((((((cosTheta_i * cosTheta_O) / v) - ((sinTheta_i * sinTheta_O) / v)) - (1.0f / v)) + 0.6931f) + logf((1.0f / (2.0f * v)))));
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = exp(((((((costheta_i * costheta_o) / v) - ((sintheta_i * sintheta_o) / v)) - (1.0e0 / v)) + 0.6931e0) + log((1.0e0 / (2.0e0 * v)))))
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return exp(Float32(Float32(Float32(Float32(Float32(Float32(cosTheta_i * cosTheta_O) / v) - Float32(Float32(sinTheta_i * sinTheta_O) / v)) - Float32(Float32(1.0) / v)) + Float32(0.6931)) + log(Float32(Float32(1.0) / Float32(Float32(2.0) * v))))) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = exp(((((((cosTheta_i * cosTheta_O) / v) - ((sinTheta_i * sinTheta_O) / v)) - (single(1.0) / v)) + single(0.6931)) + log((single(1.0) / (single(2.0) * v))))); end
\begin{array}{l}
\\
e^{\left(\left(\left(\frac{cosTheta\_i \cdot cosTheta\_O}{v} - \frac{sinTheta\_i \cdot sinTheta\_O}{v}\right) - \frac{1}{v}\right) + 0.6931\right) + \log \left(\frac{1}{2 \cdot v}\right)}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 12 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
:precision binary32
(exp
(+
(+
(-
(- (/ (* cosTheta_i cosTheta_O) v) (/ (* sinTheta_i sinTheta_O) v))
(/ 1.0 v))
0.6931)
(log (/ 1.0 (* 2.0 v))))))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((((((cosTheta_i * cosTheta_O) / v) - ((sinTheta_i * sinTheta_O) / v)) - (1.0f / v)) + 0.6931f) + logf((1.0f / (2.0f * v)))));
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = exp(((((((costheta_i * costheta_o) / v) - ((sintheta_i * sintheta_o) / v)) - (1.0e0 / v)) + 0.6931e0) + log((1.0e0 / (2.0e0 * v)))))
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return exp(Float32(Float32(Float32(Float32(Float32(Float32(cosTheta_i * cosTheta_O) / v) - Float32(Float32(sinTheta_i * sinTheta_O) / v)) - Float32(Float32(1.0) / v)) + Float32(0.6931)) + log(Float32(Float32(1.0) / Float32(Float32(2.0) * v))))) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = exp(((((((cosTheta_i * cosTheta_O) / v) - ((sinTheta_i * sinTheta_O) / v)) - (single(1.0) / v)) + single(0.6931)) + log((single(1.0) / (single(2.0) * v))))); end
\begin{array}{l}
\\
e^{\left(\left(\left(\frac{cosTheta\_i \cdot cosTheta\_O}{v} - \frac{sinTheta\_i \cdot sinTheta\_O}{v}\right) - \frac{1}{v}\right) + 0.6931\right) + \log \left(\frac{1}{2 \cdot v}\right)}
\end{array}
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (exp (+ (/ (+ (fma cosTheta_i cosTheta_O (* sinTheta_i (- sinTheta_O))) -1.0) v) (- 0.6931 (log (* v 2.0))))))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf((((fmaf(cosTheta_i, cosTheta_O, (sinTheta_i * -sinTheta_O)) + -1.0f) / v) + (0.6931f - logf((v * 2.0f)))));
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return exp(Float32(Float32(Float32(fma(cosTheta_i, cosTheta_O, Float32(sinTheta_i * Float32(-sinTheta_O))) + Float32(-1.0)) / v) + Float32(Float32(0.6931) - log(Float32(v * Float32(2.0)))))) end
\begin{array}{l}
\\
e^{\frac{\mathsf{fma}\left(cosTheta\_i, cosTheta\_O, sinTheta\_i \cdot \left(-sinTheta\_O\right)\right) + -1}{v} + \left(0.6931 - \log \left(v \cdot 2\right)\right)}
\end{array}
Initial program 99.4%
lift-+.f32N/A
lift-+.f32N/A
associate-+l+N/A
lower-+.f32N/A
Applied rewrites99.8%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
:precision binary32
(/
(exp
(/
(+
-1.0
(fma sinTheta_O (- sinTheta_i) (fma 0.6931 v (* cosTheta_i cosTheta_O))))
v))
(* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((-1.0f + fmaf(sinTheta_O, -sinTheta_i, fmaf(0.6931f, v, (cosTheta_i * cosTheta_O)))) / v)) / (v * 2.0f);
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(Float32(-1.0) + fma(sinTheta_O, Float32(-sinTheta_i), fma(Float32(0.6931), v, Float32(cosTheta_i * cosTheta_O)))) / v)) / Float32(v * Float32(2.0))) end
\begin{array}{l}
\\
\frac{e^{\frac{-1 + \mathsf{fma}\left(sinTheta\_O, -sinTheta\_i, \mathsf{fma}\left(0.6931, v, cosTheta\_i \cdot cosTheta\_O\right)\right)}{v}}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
Taylor expanded in v around 0
lower-/.f32N/A
sub-negN/A
metadata-evalN/A
lower-+.f32N/A
mul-1-negN/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-fma.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Final simplification99.7%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
:precision binary32
(/
(exp
(+
(/ (+ (fma cosTheta_i cosTheta_O (* sinTheta_i (- sinTheta_O))) -1.0) v)
0.6931))
(* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf((((fmaf(cosTheta_i, cosTheta_O, (sinTheta_i * -sinTheta_O)) + -1.0f) / v) + 0.6931f)) / (v * 2.0f);
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(Float32(fma(cosTheta_i, cosTheta_O, Float32(sinTheta_i * Float32(-sinTheta_O))) + Float32(-1.0)) / v) + Float32(0.6931))) / Float32(v * Float32(2.0))) end
\begin{array}{l}
\\
\frac{e^{\frac{\mathsf{fma}\left(cosTheta\_i, cosTheta\_O, sinTheta\_i \cdot \left(-sinTheta\_O\right)\right) + -1}{v} + 0.6931}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (/ (exp (/ (+ -1.0 (fma sinTheta_O (- sinTheta_i) (* v 0.6931))) v)) (* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((-1.0f + fmaf(sinTheta_O, -sinTheta_i, (v * 0.6931f))) / v)) / (v * 2.0f);
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(Float32(-1.0) + fma(sinTheta_O, Float32(-sinTheta_i), Float32(v * Float32(0.6931)))) / v)) / Float32(v * Float32(2.0))) end
\begin{array}{l}
\\
\frac{e^{\frac{-1 + \mathsf{fma}\left(sinTheta\_O, -sinTheta\_i, v \cdot 0.6931\right)}{v}}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
Taylor expanded in v around 0
lower-/.f32N/A
sub-negN/A
metadata-evalN/A
lower-+.f32N/A
mul-1-negN/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-fma.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in v around inf
Applied rewrites99.7%
Final simplification99.7%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (/ (exp (+ 0.6931 (/ (fma sinTheta_O (- sinTheta_i) -1.0) v))) (* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf((0.6931f + (fmaf(sinTheta_O, -sinTheta_i, -1.0f) / v))) / (v * 2.0f);
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(0.6931) + Float32(fma(sinTheta_O, Float32(-sinTheta_i), Float32(-1.0)) / v))) / Float32(v * Float32(2.0))) end
\begin{array}{l}
\\
\frac{e^{0.6931 + \frac{\mathsf{fma}\left(sinTheta\_O, -sinTheta\_i, -1\right)}{v}}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
Taylor expanded in cosTheta_i around 0
sub-negN/A
mul-1-negN/A
distribute-rgt-neg-inN/A
mul-1-negN/A
metadata-evalN/A
lower-fma.f32N/A
mul-1-negN/A
lower-neg.f3299.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (/ (exp (+ 0.6931 (/ (fma cosTheta_O cosTheta_i -1.0) v))) (* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf((0.6931f + (fmaf(cosTheta_O, cosTheta_i, -1.0f) / v))) / (v * 2.0f);
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(0.6931) + Float32(fma(cosTheta_O, cosTheta_i, Float32(-1.0)) / v))) / Float32(v * Float32(2.0))) end
\begin{array}{l}
\\
\frac{e^{0.6931 + \frac{\mathsf{fma}\left(cosTheta\_O, cosTheta\_i, -1\right)}{v}}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
Taylor expanded in sinTheta_i around 0
sub-negN/A
metadata-evalN/A
lower-fma.f3299.6
Applied rewrites99.6%
Final simplification99.6%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (/ (exp (/ (+ -1.0 (* v 0.6931)) v)) (* v 2.0)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((-1.0f + (v * 0.6931f)) / v)) / (v * 2.0f);
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = exp((((-1.0e0) + (v * 0.6931e0)) / v)) / (v * 2.0e0)
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(exp(Float32(Float32(Float32(-1.0) + Float32(v * Float32(0.6931))) / v)) / Float32(v * Float32(2.0))) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = exp(((single(-1.0) + (v * single(0.6931))) / v)) / (v * single(2.0)); end
\begin{array}{l}
\\
\frac{e^{\frac{-1 + v \cdot 0.6931}{v}}}{v \cdot 2}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
exp-sumN/A
lift-log.f32N/A
rem-exp-logN/A
lift-/.f32N/A
un-div-invN/A
lower-/.f32N/A
Applied rewrites99.7%
Taylor expanded in v around 0
lower-/.f32N/A
sub-negN/A
metadata-evalN/A
lower-+.f32N/A
mul-1-negN/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-fma.f32N/A
lower-*.f3299.7
Applied rewrites99.7%
Taylor expanded in v around inf
Applied rewrites99.5%
Final simplification99.5%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (/ (* 0.5 (exp (+ 0.6931 (/ -1.0 v)))) v))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return (0.5f * expf((0.6931f + (-1.0f / v)))) / v;
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = (0.5e0 * exp((0.6931e0 + ((-1.0e0) / v)))) / v
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(Float32(Float32(0.5) * exp(Float32(Float32(0.6931) + Float32(Float32(-1.0) / v)))) / v) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = (single(0.5) * exp((single(0.6931) + (single(-1.0) / v)))) / v; end
\begin{array}{l}
\\
\frac{0.5 \cdot e^{0.6931 + \frac{-1}{v}}}{v}
\end{array}
Initial program 99.4%
Taylor expanded in cosTheta_i around 0
+-commutativeN/A
associate--l+N/A
exp-sumN/A
lower-*.f32N/A
rem-exp-logN/A
lower-/.f32N/A
lower-exp.f32N/A
sub-negN/A
lower-+.f32N/A
distribute-neg-inN/A
mul-1-negN/A
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
metadata-evalN/A
distribute-neg-fracN/A
distribute-rgt1-inN/A
+-commutativeN/A
Applied rewrites99.3%
Taylor expanded in sinTheta_O around 0
Applied rewrites99.5%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (exp (/ (fma cosTheta_O cosTheta_i -1.0) v)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf((fmaf(cosTheta_O, cosTheta_i, -1.0f) / v));
}
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return exp(Float32(fma(cosTheta_O, cosTheta_i, Float32(-1.0)) / v)) end
\begin{array}{l}
\\
e^{\frac{\mathsf{fma}\left(cosTheta\_O, cosTheta\_i, -1\right)}{v}}
\end{array}
Initial program 99.4%
lift-+.f32N/A
lift-+.f32N/A
associate-+l+N/A
lower-+.f32N/A
Applied rewrites99.8%
Taylor expanded in v around 0
lower-/.f32N/A
associate--l+N/A
mul-1-negN/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f32N/A
mul-1-negN/A
lower-neg.f32N/A
sub-negN/A
metadata-evalN/A
lower-fma.f3298.0
Applied rewrites98.0%
Taylor expanded in sinTheta_O around 0
Applied rewrites98.0%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (* 1.0 (exp (/ -1.0 v))))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return 1.0f * expf((-1.0f / v));
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = 1.0e0 * exp(((-1.0e0) / v))
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(Float32(1.0) * exp(Float32(Float32(-1.0) / v))) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = single(1.0) * exp((single(-1.0) / v)); end
\begin{array}{l}
\\
1 \cdot e^{\frac{-1}{v}}
\end{array}
Initial program 99.4%
lift-exp.f32N/A
lift-+.f32N/A
lift-+.f32N/A
associate-+l+N/A
lift--.f32N/A
sub-negN/A
associate-+l+N/A
exp-sumN/A
lower-*.f32N/A
Applied rewrites85.4%
Taylor expanded in v around inf
Applied rewrites99.5%
Taylor expanded in v around 0
lower-/.f3298.0
Applied rewrites98.0%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (exp (/ (* cosTheta_i cosTheta_O) v)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return expf(((cosTheta_i * cosTheta_O) / v));
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = exp(((costheta_i * costheta_o) / v))
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return exp(Float32(Float32(cosTheta_i * cosTheta_O) / v)) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = exp(((cosTheta_i * cosTheta_O) / v)); end
\begin{array}{l}
\\
e^{\frac{cosTheta\_i \cdot cosTheta\_O}{v}}
\end{array}
Initial program 99.4%
lift-+.f32N/A
lift-+.f32N/A
associate-+l+N/A
lower-+.f32N/A
Applied rewrites99.8%
Taylor expanded in cosTheta_i around inf
lower-/.f32N/A
lower-*.f3211.0
Applied rewrites11.0%
Final simplification11.0%
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v) :precision binary32 (* (/ 0.5 v) (exp 0.6931)))
float code(float cosTheta_i, float cosTheta_O, float sinTheta_i, float sinTheta_O, float v) {
return (0.5f / v) * expf(0.6931f);
}
real(4) function code(costheta_i, costheta_o, sintheta_i, sintheta_o, v)
real(4), intent (in) :: costheta_i
real(4), intent (in) :: costheta_o
real(4), intent (in) :: sintheta_i
real(4), intent (in) :: sintheta_o
real(4), intent (in) :: v
code = (0.5e0 / v) * exp(0.6931e0)
end function
function code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) return Float32(Float32(Float32(0.5) / v) * exp(Float32(0.6931))) end
function tmp = code(cosTheta_i, cosTheta_O, sinTheta_i, sinTheta_O, v) tmp = (single(0.5) / v) * exp(single(0.6931)); end
\begin{array}{l}
\\
\frac{0.5}{v} \cdot e^{0.6931}
\end{array}
Initial program 99.4%
Taylor expanded in v around inf
log-recN/A
mul-1-negN/A
associate-+r+N/A
+-commutativeN/A
exp-sumN/A
mul-1-negN/A
log-recN/A
rem-exp-logN/A
lower-*.f32N/A
lower-/.f32N/A
+-commutativeN/A
exp-sumN/A
rem-exp-logN/A
lower-*.f32N/A
lower-exp.f324.6
Applied rewrites4.6%
Applied rewrites4.6%
herbie shell --seed 2024226
(FPCore (cosTheta_i cosTheta_O sinTheta_i sinTheta_O v)
:name "HairBSDF, Mp, lower"
:precision binary32
:pre (and (and (and (and (and (<= -1.0 cosTheta_i) (<= cosTheta_i 1.0)) (and (<= -1.0 cosTheta_O) (<= cosTheta_O 1.0))) (and (<= -1.0 sinTheta_i) (<= sinTheta_i 1.0))) (and (<= -1.0 sinTheta_O) (<= sinTheta_O 1.0))) (and (<= -1.5707964 v) (<= v 0.1)))
(exp (+ (+ (- (- (/ (* cosTheta_i cosTheta_O) v) (/ (* sinTheta_i sinTheta_O) v)) (/ 1.0 v)) 0.6931) (log (/ 1.0 (* 2.0 v))))))