
(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 6 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(alpha * Float32(Float32(-alpha) * log1p(Float32(-u0)))) end
\begin{array}{l}
\\
\alpha \cdot \left(\left(-\alpha\right) \cdot \mathsf{log1p}\left(-u0\right)\right)
\end{array}
Initial program 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
(FPCore (alpha u0)
:precision binary32
(*
alpha
(*
u0
(+
alpha
(* alpha (* u0 (+ 0.5 (* u0 (+ 0.3333333333333333 (* u0 0.25))))))))))
float code(float alpha, float u0) {
return alpha * (u0 * (alpha + (alpha * (u0 * (0.5f + (u0 * (0.3333333333333333f + (u0 * 0.25f))))))));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = alpha * (u0 * (alpha + (alpha * (u0 * (0.5e0 + (u0 * (0.3333333333333333e0 + (u0 * 0.25e0))))))))
end function
function code(alpha, u0) return Float32(alpha * Float32(u0 * Float32(alpha + Float32(alpha * Float32(u0 * Float32(Float32(0.5) + Float32(u0 * Float32(Float32(0.3333333333333333) + Float32(u0 * Float32(0.25)))))))))) end
function tmp = code(alpha, u0) tmp = alpha * (u0 * (alpha + (alpha * (u0 * (single(0.5) + (u0 * (single(0.3333333333333333) + (u0 * single(0.25))))))))); end
\begin{array}{l}
\\
\alpha \cdot \left(u0 \cdot \left(\alpha + \alpha \cdot \left(u0 \cdot \left(0.5 + u0 \cdot \left(0.3333333333333333 + u0 \cdot 0.25\right)\right)\right)\right)\right)
\end{array}
Initial program 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
Taylor expanded in u0 around 0 95.2%
Taylor expanded in alpha around 0 95.2%
*-commutative95.2%
Simplified95.2%
(FPCore (alpha u0) :precision binary32 (* alpha (* u0 (+ alpha (* alpha (* u0 (+ 0.5 (* u0 0.3333333333333333))))))))
float code(float alpha, float u0) {
return alpha * (u0 * (alpha + (alpha * (u0 * (0.5f + (u0 * 0.3333333333333333f))))));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = alpha * (u0 * (alpha + (alpha * (u0 * (0.5e0 + (u0 * 0.3333333333333333e0))))))
end function
function code(alpha, u0) return Float32(alpha * Float32(u0 * Float32(alpha + Float32(alpha * Float32(u0 * Float32(Float32(0.5) + Float32(u0 * Float32(0.3333333333333333)))))))) end
function tmp = code(alpha, u0) tmp = alpha * (u0 * (alpha + (alpha * (u0 * (single(0.5) + (u0 * single(0.3333333333333333))))))); end
\begin{array}{l}
\\
\alpha \cdot \left(u0 \cdot \left(\alpha + \alpha \cdot \left(u0 \cdot \left(0.5 + u0 \cdot 0.3333333333333333\right)\right)\right)\right)
\end{array}
Initial program 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
Taylor expanded in u0 around 0 95.2%
Taylor expanded in u0 around 0 93.2%
*-commutative93.2%
*-commutative93.2%
associate-*r*93.2%
Simplified93.2%
Taylor expanded in alpha around 0 93.2%
Final simplification93.2%
(FPCore (alpha u0) :precision binary32 (* alpha (* u0 (+ alpha (* 0.5 (* alpha u0))))))
float code(float alpha, float u0) {
return alpha * (u0 * (alpha + (0.5f * (alpha * u0))));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = alpha * (u0 * (alpha + (0.5e0 * (alpha * u0))))
end function
function code(alpha, u0) return Float32(alpha * Float32(u0 * Float32(alpha + Float32(Float32(0.5) * Float32(alpha * u0))))) end
function tmp = code(alpha, u0) tmp = alpha * (u0 * (alpha + (single(0.5) * (alpha * u0)))); end
\begin{array}{l}
\\
\alpha \cdot \left(u0 \cdot \left(\alpha + 0.5 \cdot \left(\alpha \cdot u0\right)\right)\right)
\end{array}
Initial program 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
Taylor expanded in u0 around 0 88.6%
(FPCore (alpha u0) :precision binary32 (* alpha (* alpha (* u0 (+ 1.0 (* u0 0.5))))))
float code(float alpha, float u0) {
return alpha * (alpha * (u0 * (1.0f + (u0 * 0.5f))));
}
real(4) function code(alpha, u0)
real(4), intent (in) :: alpha
real(4), intent (in) :: u0
code = alpha * (alpha * (u0 * (1.0e0 + (u0 * 0.5e0))))
end function
function code(alpha, u0) return Float32(alpha * Float32(alpha * Float32(u0 * Float32(Float32(1.0) + Float32(u0 * Float32(0.5)))))) end
function tmp = code(alpha, u0) tmp = alpha * (alpha * (u0 * (single(1.0) + (u0 * single(0.5))))); end
\begin{array}{l}
\\
\alpha \cdot \left(\alpha \cdot \left(u0 \cdot \left(1 + u0 \cdot 0.5\right)\right)\right)
\end{array}
Initial program 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
Taylor expanded in u0 around 0 95.2%
Taylor expanded in u0 around 0 88.6%
*-commutative88.6%
associate-*l*88.6%
Simplified88.6%
Taylor expanded in alpha around 0 88.5%
Final simplification88.5%
(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 55.1%
associate-*l*55.2%
distribute-lft-neg-out55.2%
distribute-rgt-neg-in55.2%
distribute-lft-neg-out55.2%
sub-neg55.2%
log1p-define99.1%
Simplified99.1%
Taylor expanded in u0 around 0 75.2%
herbie shell --seed 2024123
(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))))