
(FPCore (s u) :precision binary32 (* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))
float code(float s, float u) {
return s * logf((1.0f / (1.0f - (4.0f * u))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * log((1.0e0 / (1.0e0 - (4.0e0 * u))))
end function
function code(s, u) return Float32(s * log(Float32(Float32(1.0) / Float32(Float32(1.0) - Float32(Float32(4.0) * u))))) end
function tmp = code(s, u) tmp = s * log((single(1.0) / (single(1.0) - (single(4.0) * u)))); end
\begin{array}{l}
\\
s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right)
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (s u) :precision binary32 (* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))
float code(float s, float u) {
return s * logf((1.0f / (1.0f - (4.0f * u))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * log((1.0e0 / (1.0e0 - (4.0e0 * u))))
end function
function code(s, u) return Float32(s * log(Float32(Float32(1.0) / Float32(Float32(1.0) - Float32(Float32(4.0) * u))))) end
function tmp = code(s, u) tmp = s * log((single(1.0) / (single(1.0) - (single(4.0) * u)))); end
\begin{array}{l}
\\
s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right)
\end{array}
(FPCore (s u) :precision binary32 (* (- s) (log1p (* u -4.0))))
float code(float s, float u) {
return -s * log1pf((u * -4.0f));
}
function code(s, u) return Float32(Float32(-s) * log1p(Float32(u * Float32(-4.0)))) end
\begin{array}{l}
\\
\left(-s\right) \cdot \mathsf{log1p}\left(u \cdot -4\right)
\end{array}
Initial program 60.0%
log-rec62.3%
distribute-rgt-neg-out62.3%
distribute-lft-neg-out62.3%
cancel-sign-sub-inv62.3%
log1p-def99.3%
*-commutative99.3%
metadata-eval99.3%
Simplified99.3%
Final simplification99.3%
(FPCore (s u) :precision binary32 (* s (- (* u (- -4.0)) (* u (* u (+ -8.0 (* u -21.333333333333332)))))))
float code(float s, float u) {
return s * ((u * -(-4.0f)) - (u * (u * (-8.0f + (u * -21.333333333333332f)))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * ((u * -(-4.0e0)) - (u * (u * ((-8.0e0) + (u * (-21.333333333333332e0))))))
end function
function code(s, u) return Float32(s * Float32(Float32(u * Float32(-Float32(-4.0))) - Float32(u * Float32(u * Float32(Float32(-8.0) + Float32(u * Float32(-21.333333333333332))))))) end
function tmp = code(s, u) tmp = s * ((u * -single(-4.0)) - (u * (u * (single(-8.0) + (u * single(-21.333333333333332)))))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(--4\right) - u \cdot \left(u \cdot \left(-8 + u \cdot -21.333333333333332\right)\right)\right)
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 91.6%
+-commutative91.6%
+-commutative91.6%
associate-+l+91.6%
*-commutative91.6%
unpow291.6%
associate-*r*91.6%
unpow391.6%
unpow291.6%
associate-*r*91.6%
distribute-rgt-out91.6%
distribute-lft-out91.4%
unpow291.4%
associate-*r*91.4%
distribute-rgt-out91.4%
*-commutative91.4%
Simplified91.4%
distribute-lft-in91.4%
Applied egg-rr91.4%
distribute-rgt-in91.6%
*-commutative91.6%
distribute-lft-out91.6%
Applied egg-rr91.6%
Final simplification91.6%
(FPCore (s u) :precision binary32 (* s (* u (- (* u (- (- -8.0) (* u -21.333333333333332))) -4.0))))
float code(float s, float u) {
return s * (u * ((u * (-(-8.0f) - (u * -21.333333333333332f))) - -4.0f));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * (u * ((u * (-(-8.0e0) - (u * (-21.333333333333332e0)))) - (-4.0e0)))
end function
function code(s, u) return Float32(s * Float32(u * Float32(Float32(u * Float32(Float32(-Float32(-8.0)) - Float32(u * Float32(-21.333333333333332)))) - Float32(-4.0)))) end
function tmp = code(s, u) tmp = s * (u * ((u * (-single(-8.0) - (u * single(-21.333333333333332)))) - single(-4.0))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(u \cdot \left(\left(--8\right) - u \cdot -21.333333333333332\right) - -4\right)\right)
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 91.6%
+-commutative91.6%
+-commutative91.6%
associate-+l+91.6%
*-commutative91.6%
unpow291.6%
associate-*r*91.6%
unpow391.6%
unpow291.6%
associate-*r*91.6%
distribute-rgt-out91.6%
distribute-lft-out91.4%
unpow291.4%
associate-*r*91.4%
distribute-rgt-out91.4%
*-commutative91.4%
Simplified91.4%
Final simplification91.4%
(FPCore (s u) :precision binary32 (+ (* (* u 8.0) (* s u)) (* s (* u 4.0))))
float code(float s, float u) {
return ((u * 8.0f) * (s * u)) + (s * (u * 4.0f));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = ((u * 8.0e0) * (s * u)) + (s * (u * 4.0e0))
end function
function code(s, u) return Float32(Float32(Float32(u * Float32(8.0)) * Float32(s * u)) + Float32(s * Float32(u * Float32(4.0)))) end
function tmp = code(s, u) tmp = ((u * single(8.0)) * (s * u)) + (s * (u * single(4.0))); end
\begin{array}{l}
\\
\left(u \cdot 8\right) \cdot \left(s \cdot u\right) + s \cdot \left(u \cdot 4\right)
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 87.1%
*-commutative87.1%
associate-*l*87.2%
*-commutative87.2%
associate-*l*87.4%
distribute-lft-out87.3%
unpow287.3%
associate-*l*87.3%
distribute-lft-out87.2%
Simplified87.2%
associate-*r*86.9%
+-commutative86.9%
distribute-rgt-in87.1%
*-commutative87.1%
associate-*l*87.4%
Applied egg-rr87.4%
Final simplification87.4%
(FPCore (s u) :precision binary32 (* s (* u (+ (* u 8.0) 4.0))))
float code(float s, float u) {
return s * (u * ((u * 8.0f) + 4.0f));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * (u * ((u * 8.0e0) + 4.0e0))
end function
function code(s, u) return Float32(s * Float32(u * Float32(Float32(u * Float32(8.0)) + Float32(4.0)))) end
function tmp = code(s, u) tmp = s * (u * ((u * single(8.0)) + single(4.0))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(u \cdot 8 + 4\right)\right)
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 87.1%
*-commutative87.1%
associate-*l*87.2%
*-commutative87.2%
associate-*l*87.4%
distribute-lft-out87.3%
unpow287.3%
associate-*l*87.3%
distribute-lft-out87.2%
Simplified87.2%
Final simplification87.2%
(FPCore (s u) :precision binary32 (* (* s u) 4.0))
float code(float s, float u) {
return (s * u) * 4.0f;
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = (s * u) * 4.0e0
end function
function code(s, u) return Float32(Float32(s * u) * Float32(4.0)) end
function tmp = code(s, u) tmp = (s * u) * single(4.0); end
\begin{array}{l}
\\
\left(s \cdot u\right) \cdot 4
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 74.0%
Final simplification74.0%
(FPCore (s u) :precision binary32 (* u (* s 4.0)))
float code(float s, float u) {
return u * (s * 4.0f);
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (s * 4.0e0)
end function
function code(s, u) return Float32(u * Float32(s * Float32(4.0))) end
function tmp = code(s, u) tmp = u * (s * single(4.0)); end
\begin{array}{l}
\\
u \cdot \left(s \cdot 4\right)
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Taylor expanded in u around 0 74.0%
associate-*r*74.2%
Simplified74.2%
Final simplification74.2%
(FPCore (s u) :precision binary32 (* s 0.0))
float code(float s, float u) {
return s * 0.0f;
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * 0.0e0
end function
function code(s, u) return Float32(s * Float32(0.0)) end
function tmp = code(s, u) tmp = s * single(0.0); end
\begin{array}{l}
\\
s \cdot 0
\end{array}
Initial program 60.0%
log-rec62.3%
sub-neg62.3%
distribute-rgt-neg-out62.3%
+-commutative62.3%
distribute-rgt-neg-out62.3%
neg-mul-162.3%
metadata-eval62.3%
distribute-lft-in62.3%
metadata-eval62.3%
sub-neg62.3%
log-prod-0.0%
distribute-neg-in-0.0%
unsub-neg-0.0%
unsub-neg-0.0%
distribute-neg-in-0.0%
log-prod62.3%
sub-neg62.3%
metadata-eval62.3%
Simplified62.3%
Applied egg-rr14.7%
Final simplification14.7%
herbie shell --seed 2024018
(FPCore (s u)
:name "Disney BSSRDF, sample scattering profile, lower"
:precision binary32
:pre (and (and (<= 0.0 s) (<= s 256.0)) (and (<= 2.328306437e-10 u) (<= u 0.25)))
(* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))