
(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 6 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 99.0%
Simplified99.0%
Final simplification99.0%
(FPCore (u s) :precision binary32 (* s (log (* s PI))))
float code(float u, float s) {
return s * logf((s * ((float) M_PI)));
}
function code(u, s) return Float32(s * log(Float32(s * Float32(pi)))) end
function tmp = code(u, s) tmp = s * log((s * single(pi))); end
\begin{array}{l}
\\
s \cdot \log \left(s \cdot \pi\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 24.8%
+-commutative24.8%
fma-def24.8%
Simplified24.8%
Taylor expanded in u around 0 25.0%
Taylor expanded in s around 0 25.1%
associate-*r*25.1%
neg-mul-125.1%
mul-1-neg25.1%
Simplified25.1%
+-commutative25.1%
distribute-lft-in25.1%
add-sqr-sqrt-0.0%
sqrt-unprod13.1%
sqr-neg13.1%
sqrt-unprod7.5%
add-sqr-sqrt7.5%
add-sqr-sqrt7.5%
sqrt-unprod7.5%
sqr-neg7.5%
sqrt-unprod-0.0%
add-sqr-sqrt25.1%
add-sqr-sqrt-0.0%
sqrt-unprod25.3%
sqr-neg25.3%
sqrt-unprod25.3%
add-sqr-sqrt25.3%
Applied egg-rr25.3%
distribute-lft-out25.3%
log-prod25.3%
Simplified25.3%
Final simplification25.3%
(FPCore (u s) :precision binary32 (* 4.0 (+ (* (* u PI) 0.5) (* PI -0.25))))
float code(float u, float s) {
return 4.0f * (((u * ((float) M_PI)) * 0.5f) + (((float) M_PI) * -0.25f));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(Float32(u * Float32(pi)) * Float32(0.5)) + Float32(Float32(pi) * Float32(-0.25)))) end
function tmp = code(u, s) tmp = single(4.0) * (((u * single(pi)) * single(0.5)) + (single(pi) * single(-0.25))); end
\begin{array}{l}
\\
4 \cdot \left(\left(u \cdot \pi\right) \cdot 0.5 + \pi \cdot -0.25\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 10.7%
associate--r+10.7%
cancel-sign-sub-inv10.7%
distribute-rgt-out--10.7%
*-commutative10.7%
metadata-eval10.7%
metadata-eval10.7%
*-commutative10.7%
Simplified10.7%
Final simplification10.7%
(FPCore (u s) :precision binary32 (* 4.0 (* PI (+ -0.25 (* u 0.5)))))
float code(float u, float s) {
return 4.0f * (((float) M_PI) * (-0.25f + (u * 0.5f)));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(pi) * Float32(Float32(-0.25) + Float32(u * Float32(0.5))))) end
function tmp = code(u, s) tmp = single(4.0) * (single(pi) * (single(-0.25) + (u * single(0.5)))); end
\begin{array}{l}
\\
4 \cdot \left(\pi \cdot \left(-0.25 + u \cdot 0.5\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 10.7%
associate--r+10.7%
cancel-sign-sub-inv10.7%
distribute-rgt-out--10.7%
*-commutative10.7%
metadata-eval10.7%
metadata-eval10.7%
*-commutative10.7%
Simplified10.7%
associate-*l*10.7%
distribute-lft-out10.7%
Applied egg-rr10.7%
Final simplification10.7%
(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 99.0%
Simplified99.0%
Taylor expanded in u around 0 10.6%
neg-mul-110.6%
Simplified10.6%
Final simplification10.6%
(FPCore (u s) :precision binary32 PI)
float code(float u, float s) {
return (float) M_PI;
}
function code(u, s) return Float32(pi) end
function tmp = code(u, s) tmp = single(pi); end
\begin{array}{l}
\\
\pi
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 24.8%
+-commutative24.8%
fma-def24.8%
Simplified24.8%
Taylor expanded in u around 0 25.0%
Taylor expanded in s around inf 10.6%
add-sqr-sqrt-0.0%
sqrt-unprod3.2%
clear-num3.2%
clear-num3.2%
sqr-neg3.2%
sqrt-unprod4.6%
add-sqr-sqrt4.6%
un-div-inv4.6%
Applied egg-rr4.6%
associate-/r/4.6%
*-inverses4.6%
*-lft-identity4.6%
Simplified4.6%
Final simplification4.6%
herbie shell --seed 2024020
(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))))