
(FPCore (alpha u0) :precision binary32 (* (* (- alpha) alpha) (log (- 1.0 u0))))
float code(float alpha, float u0) {
return (-alpha * alpha) * logf((1.0f - u0));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = (-alpha * alpha) * log((1.0e0 - u0))
end function
function code(alpha, u0) return Float32(Float32(Float32(-alpha) * alpha) * log(Float32(Float32(1.0) - u0))) end
function tmp = code(alpha, u0) tmp = (-alpha * alpha) * log((single(1.0) - u0)); end
\begin{array}{l}
\\
\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (alpha u0) :precision binary32 (* (* (- alpha) alpha) (log (- 1.0 u0))))
float code(float alpha, float u0) {
return (-alpha * alpha) * logf((1.0f - u0));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = (-alpha * alpha) * log((1.0e0 - u0))
end function
function code(alpha, u0) return Float32(Float32(Float32(-alpha) * alpha) * log(Float32(Float32(1.0) - u0))) end
function tmp = code(alpha, u0) tmp = (-alpha * alpha) * log((single(1.0) - u0)); end
\begin{array}{l}
\\
\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right)
\end{array}
(FPCore (alpha u0) :precision binary32 (* (* alpha alpha) u0))
float code(float alpha, float u0) {
return (alpha * alpha) * u0;
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = (alpha * alpha) * u0
end function
function code(alpha, u0) return Float32(Float32(alpha * alpha) * u0) end
function tmp = code(alpha, u0) tmp = (alpha * alpha) * u0; end
\begin{array}{l}
\\
\left(\alpha \cdot \alpha\right) \cdot u0
\end{array}
Initial program 56.3%
Taylor expanded in u0 around 0
lower-*.f32N/A
unpow2N/A
lower-*.f3275.0
Applied rewrites75.0%
(FPCore (alpha u0)
:precision binary32
(if (<= (- 1.0 u0) 0.9987499713897705)
(* (log (- 1.0 u0)) (/ (pow alpha 3.0) (- alpha)))
(/
(*
(-
(* (* (fma (fma -0.25 u0 -0.3333333333333333) u0 -0.5) alpha) u0)
alpha)
u0)
(/ -1.0 alpha))))
float code(float alpha, float u0) {
float tmp;
if ((1.0f - u0) <= 0.9987499713897705f) {
tmp = logf((1.0f - u0)) * (powf(alpha, 3.0f) / -alpha);
} else {
tmp = ((((fmaf(fmaf(-0.25f, u0, -0.3333333333333333f), u0, -0.5f) * alpha) * u0) - alpha) * u0) / (-1.0f / alpha);
}
return tmp;
}
function code(alpha, u0) tmp = Float32(0.0) if (Float32(Float32(1.0) - u0) <= Float32(0.9987499713897705)) tmp = Float32(log(Float32(Float32(1.0) - u0)) * Float32((alpha ^ Float32(3.0)) / Float32(-alpha))); else tmp = Float32(Float32(Float32(Float32(Float32(fma(fma(Float32(-0.25), u0, Float32(-0.3333333333333333)), u0, Float32(-0.5)) * alpha) * u0) - alpha) * u0) / Float32(Float32(-1.0) / alpha)); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;1 - u0 \leq 0.9987499713897705:\\
\;\;\;\;\log \left(1 - u0\right) \cdot \frac{{\alpha}^{3}}{-\alpha}\\
\mathbf{else}:\\
\;\;\;\;\frac{\left(\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.25, u0, -0.3333333333333333\right), u0, -0.5\right) \cdot \alpha\right) \cdot u0 - \alpha\right) \cdot u0}{\frac{-1}{\alpha}}\\
\end{array}
\end{array}
if (-.f32 #s(literal 1 binary32) u0) < 0.998749971Initial program 90.1%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
clear-numN/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3290.1
Applied rewrites90.1%
lift-/.f32N/A
lift-/.f32N/A
clear-numN/A
frac-2negN/A
lift-*.f32N/A
distribute-lft-neg-inN/A
lift-*.f32N/A
distribute-rgt-neg-inN/A
lift-neg.f32N/A
sqr-negN/A
unpow3N/A
lift-pow.f32N/A
lift-neg.f32N/A
lower-/.f3290.3
Applied rewrites90.3%
if 0.998749971 < (-.f32 #s(literal 1 binary32) u0) Initial program 43.3%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
clear-numN/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3243.3
Applied rewrites43.3%
Taylor expanded in u0 around 0
mul-1-negN/A
lower-neg.f3285.9
Applied rewrites85.9%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
lift-/.f32N/A
div-invN/A
times-fracN/A
associate-*l/N/A
associate-/l*N/A
*-lft-identityN/A
lower-/.f32N/A
Applied rewrites86.1%
Taylor expanded in u0 around 0
*-commutativeN/A
lower-*.f32N/A
Applied rewrites97.9%
Final simplification60.4%
(FPCore (alpha u0)
:precision binary32
(if (<= u0 0.0012499999720603228)
(/
(*
(-
(* (* (fma (fma -0.25 u0 -0.3333333333333333) u0 -0.5) alpha) u0)
alpha)
u0)
(/ -1.0 alpha))
(* (/ (* (* (- alpha) alpha) alpha) alpha) (log (- 1.0 u0)))))
float code(float alpha, float u0) {
float tmp;
if (u0 <= 0.0012499999720603228f) {
tmp = ((((fmaf(fmaf(-0.25f, u0, -0.3333333333333333f), u0, -0.5f) * alpha) * u0) - alpha) * u0) / (-1.0f / alpha);
} else {
tmp = (((-alpha * alpha) * alpha) / alpha) * logf((1.0f - u0));
}
return tmp;
}
function code(alpha, u0) tmp = Float32(0.0) if (u0 <= Float32(0.0012499999720603228)) tmp = Float32(Float32(Float32(Float32(Float32(fma(fma(Float32(-0.25), u0, Float32(-0.3333333333333333)), u0, Float32(-0.5)) * alpha) * u0) - alpha) * u0) / Float32(Float32(-1.0) / alpha)); else tmp = Float32(Float32(Float32(Float32(Float32(-alpha) * alpha) * alpha) / alpha) * log(Float32(Float32(1.0) - u0))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u0 \leq 0.0012499999720603228:\\
\;\;\;\;\frac{\left(\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.25, u0, -0.3333333333333333\right), u0, -0.5\right) \cdot \alpha\right) \cdot u0 - \alpha\right) \cdot u0}{\frac{-1}{\alpha}}\\
\mathbf{else}:\\
\;\;\;\;\frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot \log \left(1 - u0\right)\\
\end{array}
\end{array}
if u0 < 0.00124999997Initial program 43.3%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
clear-numN/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3243.3
Applied rewrites43.3%
Taylor expanded in u0 around 0
mul-1-negN/A
lower-neg.f3285.9
Applied rewrites85.9%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
lift-/.f32N/A
div-invN/A
times-fracN/A
associate-*l/N/A
associate-/l*N/A
*-lft-identityN/A
lower-/.f32N/A
Applied rewrites86.1%
Taylor expanded in u0 around 0
*-commutativeN/A
lower-*.f32N/A
Applied rewrites97.9%
if 0.00124999997 < u0 Initial program 90.1%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
lower-/.f32N/A
lower-*.f3290.2
Applied rewrites90.2%
Final simplification69.7%
(FPCore (alpha u0)
:precision binary32
(if (<= u0 0.0012499999720603228)
(/
(*
(-
(* (* (fma (fma -0.25 u0 -0.3333333333333333) u0 -0.5) alpha) u0)
alpha)
u0)
(/ -1.0 alpha))
(* (* (- alpha) alpha) (log (- 1.0 u0)))))
float code(float alpha, float u0) {
float tmp;
if (u0 <= 0.0012499999720603228f) {
tmp = ((((fmaf(fmaf(-0.25f, u0, -0.3333333333333333f), u0, -0.5f) * alpha) * u0) - alpha) * u0) / (-1.0f / alpha);
} else {
tmp = (-alpha * alpha) * logf((1.0f - u0));
}
return tmp;
}
function code(alpha, u0) tmp = Float32(0.0) if (u0 <= Float32(0.0012499999720603228)) tmp = Float32(Float32(Float32(Float32(Float32(fma(fma(Float32(-0.25), u0, Float32(-0.3333333333333333)), u0, Float32(-0.5)) * alpha) * u0) - alpha) * u0) / Float32(Float32(-1.0) / alpha)); else tmp = Float32(Float32(Float32(-alpha) * alpha) * log(Float32(Float32(1.0) - u0))); end return tmp end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;u0 \leq 0.0012499999720603228:\\
\;\;\;\;\frac{\left(\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.25, u0, -0.3333333333333333\right), u0, -0.5\right) \cdot \alpha\right) \cdot u0 - \alpha\right) \cdot u0}{\frac{-1}{\alpha}}\\
\mathbf{else}:\\
\;\;\;\;\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right)\\
\end{array}
\end{array}
if u0 < 0.00124999997Initial program 43.3%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
clear-numN/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3243.3
Applied rewrites43.3%
Taylor expanded in u0 around 0
mul-1-negN/A
lower-neg.f3285.9
Applied rewrites85.9%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
lift-/.f32N/A
div-invN/A
times-fracN/A
associate-*l/N/A
associate-/l*N/A
*-lft-identityN/A
lower-/.f32N/A
Applied rewrites86.1%
Taylor expanded in u0 around 0
*-commutativeN/A
lower-*.f32N/A
Applied rewrites97.9%
if 0.00124999997 < u0 Initial program 90.1%
Final simplification69.1%
(FPCore (alpha u0) :precision binary32 (/ (* (- (* (* (fma (fma -0.25 u0 -0.3333333333333333) u0 -0.5) alpha) u0) alpha) u0) (/ -1.0 alpha)))
float code(float alpha, float u0) {
return ((((fmaf(fmaf(-0.25f, u0, -0.3333333333333333f), u0, -0.5f) * alpha) * u0) - alpha) * u0) / (-1.0f / alpha);
}
function code(alpha, u0) return Float32(Float32(Float32(Float32(Float32(fma(fma(Float32(-0.25), u0, Float32(-0.3333333333333333)), u0, Float32(-0.5)) * alpha) * u0) - alpha) * u0) / Float32(Float32(-1.0) / alpha)) end
\begin{array}{l}
\\
\frac{\left(\left(\mathsf{fma}\left(\mathsf{fma}\left(-0.25, u0, -0.3333333333333333\right), u0, -0.5\right) \cdot \alpha\right) \cdot u0 - \alpha\right) \cdot u0}{\frac{-1}{\alpha}}
\end{array}
Initial program 56.3%
lift-*.f32N/A
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
neg-sub0N/A
distribute-lft-neg-outN/A
lift-neg.f32N/A
lift-*.f32N/A
+-lft-identityN/A
associate-*l/N/A
clear-numN/A
lower-/.f32N/A
lower-/.f32N/A
lower-*.f3256.3
Applied rewrites56.3%
Taylor expanded in u0 around 0
mul-1-negN/A
lower-neg.f3274.8
Applied rewrites74.8%
lift-*.f32N/A
lift-/.f32N/A
associate-*l/N/A
lift-/.f32N/A
lift-*.f32N/A
associate-/r*N/A
lift-/.f32N/A
div-invN/A
times-fracN/A
associate-*l/N/A
associate-/l*N/A
*-lft-identityN/A
lower-/.f32N/A
Applied rewrites74.9%
Taylor expanded in u0 around 0
*-commutativeN/A
lower-*.f32N/A
Applied rewrites88.6%
Final simplification88.9%
herbie shell --seed 2024304
(FPCore (alpha u0)
:name "Beckmann Distribution sample, tan2theta, alphax == alphay"
:precision binary32
:pre (and (and (<= 0.0001 alpha) (<= alpha 1.0)) (and (<= 2.328306437e-10 u0) (<= u0 1.0)))
(* (* (- alpha) alpha) (log (- 1.0 u0))))