
(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)) (log1p (- u0))))
float code(float alpha, float u0) {
return (alpha * -alpha) * log1pf(-u0);
}
function code(alpha, u0) return Float32(Float32(alpha * Float32(-alpha)) * log1p(Float32(-u0))) end
\begin{array}{l}
\\
\left(\alpha \cdot \left(-\alpha\right)\right) \cdot \mathsf{log1p}\left(-u0\right)
\end{array}
Initial program 60.9%
*-commutative60.9%
sub-neg60.9%
log1p-def99.0%
Simplified99.0%
Final simplification99.0%
(FPCore (alpha u0) :precision binary32 (* alpha (* alpha (- (log1p (- u0))))))
float code(float alpha, float u0) {
return alpha * (alpha * -log1pf(-u0));
}
function code(alpha, u0) return Float32(alpha * Float32(alpha * Float32(-log1p(Float32(-u0))))) end
\begin{array}{l}
\\
\alpha \cdot \left(\alpha \cdot \left(-\mathsf{log1p}\left(-u0\right)\right)\right)
\end{array}
Initial program 60.9%
associate-*l*61.0%
sub-neg61.0%
log1p-def98.9%
Simplified98.9%
Final simplification98.9%
(FPCore (alpha u0) :precision binary32 (* (* alpha alpha) (+ u0 (* u0 (* u0 (+ 0.5 (* u0 0.3333333333333333)))))))
float code(float alpha, float u0) {
return (alpha * alpha) * (u0 + (u0 * (u0 * (0.5f + (u0 * 0.3333333333333333f)))));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = (alpha * alpha) * (u0 + (u0 * (u0 * (0.5e0 + (u0 * 0.3333333333333333e0)))))
end function
function code(alpha, u0) return Float32(Float32(alpha * alpha) * Float32(u0 + Float32(u0 * Float32(u0 * Float32(Float32(0.5) + Float32(u0 * Float32(0.3333333333333333))))))) end
function tmp = code(alpha, u0) tmp = (alpha * alpha) * (u0 + (u0 * (u0 * (single(0.5) + (u0 * single(0.3333333333333333)))))); end
\begin{array}{l}
\\
\left(\alpha \cdot \alpha\right) \cdot \left(u0 + u0 \cdot \left(u0 \cdot \left(0.5 + u0 \cdot 0.3333333333333333\right)\right)\right)
\end{array}
Initial program 60.9%
associate-*l*61.0%
sub-neg61.0%
log1p-def98.9%
Simplified98.9%
Taylor expanded in u0 around 0 92.1%
associate-+r+92.1%
+-commutative92.1%
+-commutative92.1%
associate-*r*92.1%
associate-*r*92.1%
distribute-rgt-out92.1%
associate-*r*92.1%
distribute-rgt-out92.1%
unpow292.1%
unpow292.1%
unpow292.1%
Simplified92.1%
Taylor expanded in u0 around 0 90.0%
unpow290.0%
+-commutative90.0%
unpow290.0%
unpow290.0%
unpow290.0%
associate-*r*90.0%
cube-mult90.0%
associate-*r*90.0%
*-commutative90.0%
associate-*l*90.0%
distribute-rgt-in90.0%
*-commutative90.0%
associate-*l*90.0%
*-commutative90.0%
Simplified90.1%
Final simplification90.1%
(FPCore (alpha u0) :precision binary32 (* (* alpha alpha) (+ u0 (* 0.5 (* u0 u0)))))
float code(float alpha, float u0) {
return (alpha * alpha) * (u0 + (0.5f * (u0 * u0)));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = (alpha * alpha) * (u0 + (0.5e0 * (u0 * u0)))
end function
function code(alpha, u0) return Float32(Float32(alpha * alpha) * Float32(u0 + Float32(Float32(0.5) * Float32(u0 * u0)))) end
function tmp = code(alpha, u0) tmp = (alpha * alpha) * (u0 + (single(0.5) * (u0 * u0))); end
\begin{array}{l}
\\
\left(\alpha \cdot \alpha\right) \cdot \left(u0 + 0.5 \cdot \left(u0 \cdot u0\right)\right)
\end{array}
Initial program 60.9%
associate-*l*61.0%
sub-neg61.0%
log1p-def98.9%
Simplified98.9%
Taylor expanded in u0 around 0 85.5%
+-commutative85.5%
associate-*r*85.5%
distribute-rgt-out85.5%
unpow285.5%
unpow285.5%
Simplified85.5%
Final simplification85.5%
(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(alpha * Float32(alpha * u0)) end
function tmp = code(alpha, u0) tmp = alpha * (alpha * u0); end
\begin{array}{l}
\\
\alpha \cdot \left(\alpha \cdot u0\right)
\end{array}
Initial program 60.9%
associate-*l*61.0%
sub-neg61.0%
log1p-def98.9%
Simplified98.9%
Taylor expanded in u0 around 0 71.0%
*-commutative71.0%
unpow271.0%
associate-*l*71.0%
Simplified71.0%
Final simplification71.0%
herbie shell --seed 2023174
(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))))