
(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 14 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 (fma (log1p (* 4.0 u)) s (* (log1p (* u (* u -16.0))) (- s))))
float code(float s, float u) {
return fmaf(log1pf((4.0f * u)), s, (log1pf((u * (u * -16.0f))) * -s));
}
function code(s, u) return fma(log1p(Float32(Float32(4.0) * u)), s, Float32(log1p(Float32(u * Float32(u * Float32(-16.0)))) * Float32(-s))) end
\begin{array}{l}
\\
\mathsf{fma}\left(\mathsf{log1p}\left(4 \cdot u\right), s, \mathsf{log1p}\left(u \cdot \left(u \cdot -16\right)\right) \cdot \left(-s\right)\right)
\end{array}
Initial program 58.1%
Applied egg-rr99.2%
sub-negN/A
distribute-rgt-inN/A
fma-defineN/A
fma-lowering-fma.f32N/A
log1p-defineN/A
log1p-lowering-log1p.f32N/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
neg-lowering-neg.f32N/A
log1p-defineN/A
log1p-lowering-log1p.f32N/A
associate-*l*N/A
*-lowering-*.f32N/A
*-lowering-*.f3299.4%
Applied egg-rr99.4%
Final simplification99.4%
(FPCore (s u) :precision binary32 (* (log1p (* u -4.0)) (- s)))
float code(float s, float u) {
return log1pf((u * -4.0f)) * -s;
}
function code(s, u) return Float32(log1p(Float32(u * Float32(-4.0))) * Float32(-s)) end
\begin{array}{l}
\\
\mathsf{log1p}\left(u \cdot -4\right) \cdot \left(-s\right)
\end{array}
Initial program 58.1%
log-recN/A
neg-mul-1N/A
associate-*r*N/A
*-commutativeN/A
*-lowering-*.f32N/A
sub-negN/A
log1p-defineN/A
log1p-lowering-log1p.f32N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
*-lowering-*.f32N/A
metadata-evalN/A
*-commutativeN/A
neg-mul-1N/A
neg-lowering-neg.f3299.4%
Simplified99.4%
(FPCore (s u)
:precision binary32
(*
u
(/
1.0
(+
(/ 0.25 s)
(*
u
(+
(* u (+ (/ (* u -0.6666666666666666) s) (/ -0.3333333333333333 s)))
(/ -0.5 s)))))))
float code(float s, float u) {
return u * (1.0f / ((0.25f / s) + (u * ((u * (((u * -0.6666666666666666f) / s) + (-0.3333333333333333f / s))) + (-0.5f / s)))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (1.0e0 / ((0.25e0 / s) + (u * ((u * (((u * (-0.6666666666666666e0)) / s) + ((-0.3333333333333333e0) / s))) + ((-0.5e0) / s)))))
end function
function code(s, u) return Float32(u * Float32(Float32(1.0) / Float32(Float32(Float32(0.25) / s) + Float32(u * Float32(Float32(u * Float32(Float32(Float32(u * Float32(-0.6666666666666666)) / s) + Float32(Float32(-0.3333333333333333) / s))) + Float32(Float32(-0.5) / s)))))) end
function tmp = code(s, u) tmp = u * (single(1.0) / ((single(0.25) / s) + (u * ((u * (((u * single(-0.6666666666666666)) / s) + (single(-0.3333333333333333) / s))) + (single(-0.5) / s))))); end
\begin{array}{l}
\\
u \cdot \frac{1}{\frac{0.25}{s} + u \cdot \left(u \cdot \left(\frac{u \cdot -0.6666666666666666}{s} + \frac{-0.3333333333333333}{s}\right) + \frac{-0.5}{s}\right)}
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
distribute-rgt-inN/A
associate-*r*N/A
associate-+r+N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-commutativeN/A
associate-*l*N/A
unpow2N/A
Simplified94.1%
flip-+N/A
fmm-defN/A
clear-numN/A
/-lowering-/.f32N/A
Applied egg-rr93.7%
Taylor expanded in u around 0
+-commutativeN/A
+-lowering-+.f32N/A
associate-*r/N/A
metadata-evalN/A
/-lowering-/.f32N/A
*-lowering-*.f32N/A
sub-negN/A
+-lowering-+.f32N/A
Simplified95.0%
(FPCore (s u) :precision binary32 (* u (+ (+ (* (+ 21.333333333333332 (* u 64.0)) (* s (* u u))) (* 4.0 s)) (* s (* u 8.0)))))
float code(float s, float u) {
return u * ((((21.333333333333332f + (u * 64.0f)) * (s * (u * u))) + (4.0f * s)) + (s * (u * 8.0f)));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * ((((21.333333333333332e0 + (u * 64.0e0)) * (s * (u * u))) + (4.0e0 * s)) + (s * (u * 8.0e0)))
end function
function code(s, u) return Float32(u * Float32(Float32(Float32(Float32(Float32(21.333333333333332) + Float32(u * Float32(64.0))) * Float32(s * Float32(u * u))) + Float32(Float32(4.0) * s)) + Float32(s * Float32(u * Float32(8.0))))) end
function tmp = code(s, u) tmp = u * ((((single(21.333333333333332) + (u * single(64.0))) * (s * (u * u))) + (single(4.0) * s)) + (s * (u * single(8.0)))); end
\begin{array}{l}
\\
u \cdot \left(\left(\left(21.333333333333332 + u \cdot 64\right) \cdot \left(s \cdot \left(u \cdot u\right)\right) + 4 \cdot s\right) + s \cdot \left(u \cdot 8\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
distribute-rgt-inN/A
associate-*r*N/A
associate-+r+N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-commutativeN/A
associate-*l*N/A
unpow2N/A
Simplified94.1%
+-commutativeN/A
distribute-rgt-inN/A
*-commutativeN/A
associate-+r+N/A
+-lowering-+.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
associate-*l*N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-lowering-*.f3294.3%
Applied egg-rr94.3%
Final simplification94.3%
(FPCore (s u) :precision binary32 (* u (* s (+ 4.0 (* u (+ 8.0 (* u (+ 21.333333333333332 (* u 64.0)))))))))
float code(float s, float u) {
return u * (s * (4.0f + (u * (8.0f + (u * (21.333333333333332f + (u * 64.0f)))))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (s * (4.0e0 + (u * (8.0e0 + (u * (21.333333333333332e0 + (u * 64.0e0)))))))
end function
function code(s, u) return Float32(u * Float32(s * Float32(Float32(4.0) + Float32(u * Float32(Float32(8.0) + Float32(u * Float32(Float32(21.333333333333332) + Float32(u * Float32(64.0))))))))) end
function tmp = code(s, u) tmp = u * (s * (single(4.0) + (u * (single(8.0) + (u * (single(21.333333333333332) + (u * single(64.0)))))))); end
\begin{array}{l}
\\
u \cdot \left(s \cdot \left(4 + u \cdot \left(8 + u \cdot \left(21.333333333333332 + u \cdot 64\right)\right)\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
distribute-rgt-inN/A
associate-*r*N/A
associate-+r+N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-commutativeN/A
associate-*l*N/A
unpow2N/A
Simplified94.1%
Taylor expanded in s around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
unpow2N/A
associate-*r*N/A
distribute-lft-inN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3294.2%
Simplified94.2%
(FPCore (s u) :precision binary32 (* s (* u (+ 4.0 (* u (+ 8.0 (* u (+ 21.333333333333332 (* u 64.0)))))))))
float code(float s, float u) {
return s * (u * (4.0f + (u * (8.0f + (u * (21.333333333333332f + (u * 64.0f)))))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * (u * (4.0e0 + (u * (8.0e0 + (u * (21.333333333333332e0 + (u * 64.0e0)))))))
end function
function code(s, u) return Float32(s * Float32(u * Float32(Float32(4.0) + Float32(u * Float32(Float32(8.0) + Float32(u * Float32(Float32(21.333333333333332) + Float32(u * Float32(64.0))))))))) end
function tmp = code(s, u) tmp = s * (u * (single(4.0) + (u * (single(8.0) + (u * (single(21.333333333333332) + (u * single(64.0)))))))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(4 + u \cdot \left(8 + u \cdot \left(21.333333333333332 + u \cdot 64\right)\right)\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3294.1%
Simplified94.1%
(FPCore (s u) :precision binary32 (* u (+ (* 4.0 s) (* u (* s (+ 8.0 (* u 21.333333333333332)))))))
float code(float s, float u) {
return u * ((4.0f * s) + (u * (s * (8.0f + (u * 21.333333333333332f)))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * ((4.0e0 * s) + (u * (s * (8.0e0 + (u * 21.333333333333332e0)))))
end function
function code(s, u) return Float32(u * Float32(Float32(Float32(4.0) * s) + Float32(u * Float32(s * Float32(Float32(8.0) + Float32(u * Float32(21.333333333333332))))))) end
function tmp = code(s, u) tmp = u * ((single(4.0) * s) + (u * (s * (single(8.0) + (u * single(21.333333333333332)))))); end
\begin{array}{l}
\\
u \cdot \left(4 \cdot s + u \cdot \left(s \cdot \left(8 + u \cdot 21.333333333333332\right)\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3292.6%
Simplified92.6%
Final simplification92.6%
(FPCore (s u) :precision binary32 (* u (* s (+ 4.0 (* u (+ 8.0 (* u 21.333333333333332)))))))
float code(float s, float u) {
return u * (s * (4.0f + (u * (8.0f + (u * 21.333333333333332f)))));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (s * (4.0e0 + (u * (8.0e0 + (u * 21.333333333333332e0)))))
end function
function code(s, u) return Float32(u * Float32(s * Float32(Float32(4.0) + Float32(u * Float32(Float32(8.0) + Float32(u * Float32(21.333333333333332))))))) end
function tmp = code(s, u) tmp = u * (s * (single(4.0) + (u * (single(8.0) + (u * single(21.333333333333332)))))); end
\begin{array}{l}
\\
u \cdot \left(s \cdot \left(4 + u \cdot \left(8 + u \cdot 21.333333333333332\right)\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-lowering-*.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3292.6%
Simplified92.6%
Taylor expanded in s around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3292.5%
Simplified92.5%
(FPCore (s u) :precision binary32 (* s (* u (+ 4.0 (* u (+ 8.0 (* u 21.333333333333332)))))))
float code(float s, float u) {
return s * (u * (4.0f + (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 * (8.0e0 + (u * 21.333333333333332e0)))))
end function
function code(s, u) return Float32(s * Float32(u * Float32(Float32(4.0) + Float32(u * Float32(Float32(8.0) + Float32(u * Float32(21.333333333333332))))))) end
function tmp = code(s, u) tmp = s * (u * (single(4.0) + (u * (single(8.0) + (u * single(21.333333333333332)))))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(4 + u \cdot \left(8 + u \cdot 21.333333333333332\right)\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3292.4%
Simplified92.4%
(FPCore (s u) :precision binary32 (* u (/ s (+ 0.25 (* u -0.5)))))
float code(float s, float u) {
return u * (s / (0.25f + (u * -0.5f)));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (s / (0.25e0 + (u * (-0.5e0))))
end function
function code(s, u) return Float32(u * Float32(s / Float32(Float32(0.25) + Float32(u * Float32(-0.5))))) end
function tmp = code(s, u) tmp = u * (s / (single(0.25) + (u * single(-0.5)))); end
\begin{array}{l}
\\
u \cdot \frac{s}{0.25 + u \cdot -0.5}
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
distribute-rgt-inN/A
associate-*r*N/A
associate-+r+N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-commutativeN/A
associate-*l*N/A
unpow2N/A
Simplified94.1%
flip-+N/A
fmm-defN/A
clear-numN/A
/-lowering-/.f32N/A
Applied egg-rr93.7%
Taylor expanded in u around 0
+-lowering-+.f32N/A
associate-*r/N/A
/-lowering-/.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
associate-*r/N/A
metadata-evalN/A
/-lowering-/.f3290.1%
Simplified90.1%
Taylor expanded in s around 0
/-lowering-/.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3290.4%
Simplified90.4%
(FPCore (s u) :precision binary32 (* u (* s (+ 4.0 (* u 8.0)))))
float code(float s, float u) {
return u * (s * (4.0f + (u * 8.0f)));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = u * (s * (4.0e0 + (u * 8.0e0)))
end function
function code(s, u) return Float32(u * Float32(s * Float32(Float32(4.0) + Float32(u * Float32(8.0))))) end
function tmp = code(s, u) tmp = u * (s * (single(4.0) + (u * single(8.0)))); end
\begin{array}{l}
\\
u \cdot \left(s \cdot \left(4 + u \cdot 8\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3288.7%
Simplified88.7%
(FPCore (s u) :precision binary32 (* s (* u (+ 4.0 (* u 8.0)))))
float code(float s, float u) {
return s * (u * (4.0f + (u * 8.0f)));
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * (u * (4.0e0 + (u * 8.0e0)))
end function
function code(s, u) return Float32(s * Float32(u * Float32(Float32(4.0) + Float32(u * Float32(8.0))))) end
function tmp = code(s, u) tmp = s * (u * (single(4.0) + (u * single(8.0)))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(4 + u \cdot 8\right)\right)
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f3288.7%
Simplified88.7%
(FPCore (s u) :precision binary32 (* (* 4.0 u) s))
float code(float s, float u) {
return (4.0f * u) * s;
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = (4.0e0 * u) * s
end function
function code(s, u) return Float32(Float32(Float32(4.0) * u) * s) end
function tmp = code(s, u) tmp = (single(4.0) * u) * s; end
\begin{array}{l}
\\
\left(4 \cdot u\right) \cdot s
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-lowering-*.f3276.7%
Simplified76.7%
Final simplification76.7%
(FPCore (s u) :precision binary32 (* s -2.0))
float code(float s, float u) {
return s * -2.0f;
}
real(4) function code(s, u)
real(4), intent (in) :: s
real(4), intent (in) :: u
code = s * (-2.0e0)
end function
function code(s, u) return Float32(s * Float32(-2.0)) end
function tmp = code(s, u) tmp = s * single(-2.0); end
\begin{array}{l}
\\
s \cdot -2
\end{array}
Initial program 58.1%
Taylor expanded in u around 0
*-lowering-*.f32N/A
distribute-rgt-inN/A
associate-*r*N/A
associate-+r+N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-commutativeN/A
associate-*l*N/A
*-commutativeN/A
distribute-lft-outN/A
*-lowering-*.f32N/A
+-lowering-+.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
*-commutativeN/A
associate-*l*N/A
unpow2N/A
Simplified94.1%
flip-+N/A
fmm-defN/A
clear-numN/A
/-lowering-/.f32N/A
Applied egg-rr93.7%
Taylor expanded in u around 0
+-lowering-+.f32N/A
associate-*r/N/A
/-lowering-/.f32N/A
*-commutativeN/A
*-lowering-*.f32N/A
associate-*r/N/A
metadata-evalN/A
/-lowering-/.f3290.1%
Simplified90.1%
Taylor expanded in u around inf
*-commutativeN/A
*-lowering-*.f328.2%
Simplified8.2%
herbie shell --seed 2024139
(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))))))