
(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 10 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 98.9%
Simplified98.9%
Final simplification98.9%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+ -1.0 (/ 1.0 (+ (/ u 2.0) (/ (- 1.0 u) (+ 1.0 (pow E (/ PI s)))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / 2.0f) + ((1.0f - u) / (1.0f + powf(((float) M_E), (((float) M_PI) / s))))))));
}
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) + (Float32(exp(1)) ^ Float32(Float32(pi) / s)))))))))) 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) + (single(2.71828182845904523536) ^ (single(pi) / s)))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{u}{2} + \frac{1 - u}{1 + {e}^{\left(\frac{\pi}{s}\right)}}}\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around inf 37.8%
*-un-lft-identity37.8%
exp-prod37.8%
Applied egg-rr37.8%
exp-1-e37.8%
Simplified37.8%
Final simplification37.8%
(FPCore (u s) :precision binary32 (* s (- (log (+ -1.0 (/ 1.0 (+ (/ (- 1.0 u) (+ 1.0 (exp (/ PI s)))) (* u 0.5))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / (((1.0f - u) / (1.0f + expf((((float) M_PI) / s)))) + (u * 0.5f)))));
}
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(0.5)))))))) 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(0.5)))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{1 - u}{1 + e^{\frac{\pi}{s}}} + u \cdot 0.5}\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around inf 37.8%
*-un-lft-identity37.8%
exp-prod37.8%
Applied egg-rr37.8%
exp-1-e37.8%
Simplified37.8%
e-exp-137.8%
add-sqr-sqrt37.8%
sqrt-unprod37.8%
sqr-neg37.8%
sqrt-unprod-0.0%
add-sqr-sqrt6.4%
exp-prod6.4%
*-un-lft-identity6.4%
exp-neg6.4%
Applied egg-rr6.4%
rec-exp6.4%
distribute-neg-frac6.4%
Simplified6.4%
+-commutative6.4%
*-un-lft-identity6.4%
fma-def6.4%
clear-num6.4%
clear-num6.4%
add-sqr-sqrt-0.0%
sqrt-unprod37.8%
sqr-neg37.8%
sqrt-unprod37.8%
add-sqr-sqrt37.8%
div-inv37.8%
metadata-eval37.8%
metadata-eval37.8%
Applied egg-rr37.8%
fma-udef37.8%
*-lft-identity37.8%
*-commutative37.8%
Simplified37.8%
Final simplification37.8%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+ -1.0 (/ 1.0 (+ (/ u 2.0) (/ (- 1.0 u) (+ 1.0 (+ 1.0 (/ PI s)))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / 2.0f) + ((1.0f - u) / (1.0f + (1.0f + (((float) M_PI) / s))))))));
}
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) + Float32(Float32(1.0) + Float32(Float32(pi) / s)))))))))) 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) + (single(1.0) + (single(pi) / s)))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{u}{2} + \frac{1 - u}{1 + \left(1 + \frac{\pi}{s}\right)}}\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around inf 37.8%
Taylor expanded in s around inf 35.9%
Final simplification35.9%
(FPCore (u s) :precision binary32 (* 4.0 (* PI (- (* u 0.25) (fma u -0.25 0.25)))))
float code(float u, float s) {
return 4.0f * (((float) M_PI) * ((u * 0.25f) - fmaf(u, -0.25f, 0.25f)));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(pi) * Float32(Float32(u * Float32(0.25)) - fma(u, Float32(-0.25), Float32(0.25))))) end
\begin{array}{l}
\\
4 \cdot \left(\pi \cdot \left(u \cdot 0.25 - \mathsf{fma}\left(u, -0.25, 0.25\right)\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around inf 12.0%
sub-neg12.0%
associate-*r*12.0%
*-commutative12.0%
distribute-rgt-in12.0%
fma-def12.0%
Applied egg-rr12.0%
sub-neg12.0%
*-commutative12.0%
associate-*r*12.0%
distribute-rgt-out--12.0%
*-commutative12.0%
Simplified12.0%
Final simplification12.0%
(FPCore (u s) :precision binary32 (* -4.0 (+ (* PI (+ 0.25 (* u -0.25))) (* u (* PI -0.25)))))
float code(float u, float s) {
return -4.0f * ((((float) M_PI) * (0.25f + (u * -0.25f))) + (u * (((float) M_PI) * -0.25f)));
}
function code(u, s) return Float32(Float32(-4.0) * Float32(Float32(Float32(pi) * Float32(Float32(0.25) + Float32(u * Float32(-0.25)))) + Float32(u * Float32(Float32(pi) * Float32(-0.25))))) end
function tmp = code(u, s) tmp = single(-4.0) * ((single(pi) * (single(0.25) + (u * single(-0.25)))) + (u * (single(pi) * single(-0.25)))); end
\begin{array}{l}
\\
-4 \cdot \left(\pi \cdot \left(0.25 + u \cdot -0.25\right) + u \cdot \left(\pi \cdot -0.25\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around -inf 12.0%
associate--r+12.0%
cancel-sign-sub-inv12.0%
metadata-eval12.0%
cancel-sign-sub-inv12.0%
associate-*r*12.0%
distribute-rgt-out12.0%
*-commutative12.0%
metadata-eval12.0%
*-commutative12.0%
associate-*l*12.0%
Simplified12.0%
Final simplification12.0%
(FPCore (u s) :precision binary32 (* 4.0 (+ (* PI -0.25) (* 0.5 (* u PI)))))
float code(float u, float s) {
return 4.0f * ((((float) M_PI) * -0.25f) + (0.5f * (u * ((float) M_PI))));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(Float32(pi) * Float32(-0.25)) + Float32(Float32(0.5) * Float32(u * Float32(pi))))) end
function tmp = code(u, s) tmp = single(4.0) * ((single(pi) * single(-0.25)) + (single(0.5) * (u * single(pi)))); end
\begin{array}{l}
\\
4 \cdot \left(\pi \cdot -0.25 + 0.5 \cdot \left(u \cdot \pi\right)\right)
\end{array}
Initial program 98.9%
Simplified98.9%
Taylor expanded in s around inf 12.0%
associate--r+12.0%
cancel-sign-sub-inv12.0%
distribute-rgt-out--12.0%
*-commutative12.0%
metadata-eval12.0%
metadata-eval12.0%
*-commutative12.0%
Simplified12.0%
Final simplification12.0%
(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 98.9%
Simplified98.9%
Taylor expanded in s around inf 12.0%
associate--r+12.0%
cancel-sign-sub-inv12.0%
distribute-rgt-out--12.0%
*-commutative12.0%
metadata-eval12.0%
metadata-eval12.0%
*-commutative12.0%
Simplified12.0%
Taylor expanded in u around 0 12.0%
+-commutative12.0%
associate-*r*12.0%
distribute-rgt-out12.0%
Simplified12.0%
Final simplification12.0%
(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 98.9%
Simplified98.9%
Taylor expanded in u around 0 11.8%
neg-mul-111.8%
Simplified11.8%
Final simplification11.8%
(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 98.9%
Simplified98.9%
Taylor expanded in s around inf 37.8%
Taylor expanded in u around 0 11.8%
expm1-log1p-u-0.0%
expm1-udef-0.0%
add-sqr-sqrt-0.0%
sqrt-unprod3.2%
sqr-neg3.2%
sqrt-unprod4.5%
add-sqr-sqrt4.5%
Applied egg-rr4.5%
expm1-def4.5%
expm1-log1p4.5%
Simplified4.5%
Taylor expanded in s around 0 4.5%
Final simplification4.5%
herbie shell --seed 2024029
(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))))