
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ 1.0 (+ 1.0 (exp (/ PI s))))))
(*
(- s)
(log
(-
(/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) t_0)) t_0))
1.0)))))
float code(float u, float s) {
float t_0 = 1.0f / (1.0f + expf((((float) M_PI) / s)));
return -s * logf(((1.0f / ((u * ((1.0f / (1.0f + expf((-((float) M_PI) / s)))) - t_0)) + t_0)) - 1.0f));
}
function code(u, s) t_0 = Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))) return Float32(Float32(-s) * log(Float32(Float32(Float32(1.0) / Float32(Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) - t_0)) + t_0)) - Float32(1.0)))) end
function tmp = code(u, s) t_0 = single(1.0) / (single(1.0) + exp((single(pi) / s))); tmp = -s * log(((single(1.0) / ((u * ((single(1.0) / (single(1.0) + exp((-single(pi) / s)))) - t_0)) + t_0)) - single(1.0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\pi}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\pi}{s}}} - t_0\right) + t_0} - 1\right)
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ 1.0 (+ 1.0 (exp (/ PI s))))))
(*
(- s)
(log
(-
(/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) t_0)) t_0))
1.0)))))
float code(float u, float s) {
float t_0 = 1.0f / (1.0f + expf((((float) M_PI) / s)));
return -s * logf(((1.0f / ((u * ((1.0f / (1.0f + expf((-((float) M_PI) / s)))) - t_0)) + t_0)) - 1.0f));
}
function code(u, s) t_0 = Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))) return Float32(Float32(-s) * log(Float32(Float32(Float32(1.0) / Float32(Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(-Float32(pi)) / s)))) - t_0)) + t_0)) - Float32(1.0)))) end
function tmp = code(u, s) t_0 = single(1.0) / (single(1.0) + exp((single(pi) / s))); tmp = -s * log(((single(1.0) / ((u * ((single(1.0) / (single(1.0) + exp((-single(pi) / s)))) - t_0)) + t_0)) - single(1.0))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\pi}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\pi}{s}}} - t_0\right) + t_0} - 1\right)
\end{array}
\end{array}
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
(/
1.0
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(/ (- 1.0 u) (+ 1.0 (exp (/ PI s))))))
-1.0)))))
float code(float u, float s) {
return s * -logf(((1.0f / ((u / (1.0f + expf((((float) M_PI) / -s)))) + ((1.0f - u) / (1.0f + expf((((float) M_PI) / s)))))) + -1.0f));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(Float32(1.0) / Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))))) + Float32(-1.0))))) end
function tmp = code(u, s) tmp = s * -log(((single(1.0) / ((u / (single(1.0) + exp((single(pi) / -s)))) + ((single(1.0) - u) / (single(1.0) + exp((single(pi) / s)))))) + single(-1.0))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(\frac{1}{\frac{u}{1 + e^{\frac{\pi}{-s}}} + \frac{1 - u}{1 + e^{\frac{\pi}{s}}}} + -1\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Final simplification98.8%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
-1.0
(/ 1.0 (+ (/ u 2.0) (/ (- 1.0 u) (+ 1.0 (exp (/ 1.0 (/ s PI))))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / 2.0f) + ((1.0f - u) / (1.0f + expf((1.0f / (s / ((float) M_PI))))))))));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(-1.0) + Float32(Float32(1.0) / Float32(Float32(u / Float32(2.0)) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(1.0) / Float32(s / Float32(pi)))))))))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + (single(1.0) / ((u / single(2.0)) + ((single(1.0) - u) / (single(1.0) + exp((single(1.0) / (s / single(pi)))))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{u}{2} + \frac{1 - u}{1 + e^{\frac{1}{\frac{s}{\pi}}}}}\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 37.8%
clear-num37.8%
inv-pow37.8%
Applied egg-rr37.8%
unpow-137.8%
Applied egg-rr37.8%
Final simplification37.8%
(FPCore (u s) :precision binary32 (* s (- (log (+ -1.0 (/ 1.0 (+ (/ (- 1.0 u) (+ 1.0 (exp (/ PI s)))) (/ u 2.0))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / (((1.0f - u) / (1.0f + expf((((float) M_PI) / s)))) + (u / 2.0f)))));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(-1.0) + Float32(Float32(1.0) / Float32(Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))) + Float32(u / Float32(2.0)))))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + (single(1.0) / (((single(1.0) - u) / (single(1.0) + exp((single(pi) / s)))) + (u / single(2.0)))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{1 - u}{1 + e^{\frac{\pi}{s}}} + \frac{u}{2}}\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 37.8%
Final simplification37.8%
(FPCore (u s) :precision binary32 (* s (- (log (+ -1.0 (/ 2.0 u))))))
float code(float u, float s) {
return s * -logf((-1.0f + (2.0f / u)));
}
real(4) function code(u, s)
real(4), intent (in) :: u
real(4), intent (in) :: s
code = s * -log(((-1.0e0) + (2.0e0 / u)))
end function
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(-1.0) + Float32(Float32(2.0) / u))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + (single(2.0) / u))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{2}{u}\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 37.8%
Taylor expanded in s around inf 36.4%
Taylor expanded in s around 0 37.3%
associate-*r*37.3%
neg-mul-137.3%
sub-neg37.3%
associate-*r/37.3%
metadata-eval37.3%
metadata-eval37.3%
Simplified37.3%
Final simplification37.3%
(FPCore (u s) :precision binary32 (* (- s) (log1p (/ PI s))))
float code(float u, float s) {
return -s * log1pf((((float) M_PI) / s));
}
function code(u, s) return Float32(Float32(-s) * log1p(Float32(Float32(pi) / s))) end
\begin{array}{l}
\\
\left(-s\right) \cdot \mathsf{log1p}\left(\frac{\pi}{s}\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 37.8%
Taylor expanded in s around inf 36.4%
Taylor expanded in u around 0 25.3%
associate-*r*25.3%
neg-mul-125.3%
log1p-def25.3%
Simplified25.3%
Final simplification25.3%
(FPCore (u s) :precision binary32 (* 4.0 (* PI (+ (* u 0.5) -0.25))))
float code(float u, float s) {
return 4.0f * (((float) M_PI) * ((u * 0.5f) + -0.25f));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(pi) * Float32(Float32(u * Float32(0.5)) + Float32(-0.25)))) end
function tmp = code(u, s) tmp = single(4.0) * (single(pi) * ((u * single(0.5)) + single(-0.25))); end
\begin{array}{l}
\\
4 \cdot \left(\pi \cdot \left(u \cdot 0.5 + -0.25\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 11.6%
associate--r+11.6%
cancel-sign-sub-inv11.6%
distribute-rgt-out--11.6%
*-commutative11.6%
metadata-eval11.6%
metadata-eval11.6%
*-commutative11.6%
Simplified11.6%
Taylor expanded in u around 0 11.6%
+-commutative11.6%
associate-*r*11.6%
distribute-rgt-out11.6%
Simplified11.6%
Final simplification11.6%
(FPCore (u s) :precision binary32 (- PI))
float code(float u, float s) {
return -((float) M_PI);
}
function code(u, s) return Float32(-Float32(pi)) end
function tmp = code(u, s) tmp = -single(pi); end
\begin{array}{l}
\\
-\pi
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in u around 0 11.6%
neg-mul-111.6%
Simplified11.6%
Final simplification11.6%
herbie shell --seed 2024019
(FPCore (u s)
:name "Sample trimmed logistic on [-pi, pi]"
:precision binary32
:pre (and (and (<= 2.328306437e-10 u) (<= u 1.0)) (and (<= 0.0 s) (<= s 1.0651631)))
(* (- s) (log (- (/ 1.0 (+ (* u (- (/ 1.0 (+ 1.0 (exp (/ (- PI) s)))) (/ 1.0 (+ 1.0 (exp (/ PI s)))))) (/ 1.0 (+ 1.0 (exp (/ PI s)))))) 1.0))))