
(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 (/ 1.0 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) * (1.0f / s))))))) + -1.0f));
}
function code(u, s) return Float32(Float32(-s) * 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) * Float32(Float32(1.0) / 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) * (single(1.0) / s))))))) + single(-1.0))); end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\frac{1}{\frac{u}{1 + e^{\frac{\pi}{-s}}} + \frac{1 - u}{1 + e^{\pi \cdot \frac{1}{s}}}} + -1\right)
\end{array}
Initial program 99.0%
Simplified99.0%
clear-num99.0%
associate-/r/99.0%
Applied egg-rr99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
-1.0
(/
1.0
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(/ (- 1.0 u) (+ 1.0 (exp (/ PI s)))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / (1.0f + expf((((float) M_PI) / -s)))) + ((1.0f - u) / (1.0f + expf((((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(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(Float32(1.0) - u) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / s)))))))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + (single(1.0) / ((u / (single(1.0) + exp((single(pi) / -s)))) + ((single(1.0) - u) / (single(1.0) + exp((single(pi) / s)))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{u}{1 + e^{\frac{\pi}{-s}}} + \frac{1 - u}{1 + e^{\frac{\pi}{s}}}}\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
-1.0
(/
1.0
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(/
(- 1.0 u)
(+ 1.0 (+ 1.0 (/ (- PI (* -0.5 (/ (* PI PI) s))) s)))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / (1.0f + expf((((float) M_PI) / -s)))) + ((1.0f - u) / (1.0f + (1.0f + ((((float) M_PI) - (-0.5f * ((((float) M_PI) * ((float) M_PI)) / s))) / s))))))));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(-1.0) + 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) + Float32(Float32(1.0) + Float32(Float32(Float32(pi) - Float32(Float32(-0.5) * Float32(Float32(Float32(pi) * Float32(pi)) / s))) / s)))))))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + (single(1.0) / ((u / (single(1.0) + exp((single(pi) / -s)))) + ((single(1.0) - u) / (single(1.0) + (single(1.0) + ((single(pi) - (single(-0.5) * ((single(pi) * single(pi)) / s))) / s)))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{1}{\frac{u}{1 + e^{\frac{\pi}{-s}}} + \frac{1 - u}{1 + \left(1 + \frac{\pi - -0.5 \cdot \frac{\pi \cdot \pi}{s}}{s}\right)}}\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
clear-num99.0%
associate-/r/99.0%
Applied egg-rr99.0%
associate-*l/99.0%
*-un-lft-identity99.0%
*-un-lft-identity99.0%
exp-prod99.0%
Applied egg-rr99.0%
exp-1-e99.0%
Simplified99.0%
Taylor expanded in s around -inf 91.0%
mul-1-neg91.0%
unsub-neg91.0%
Simplified91.0%
unpow291.0%
Applied egg-rr91.0%
Final simplification91.0%
(FPCore (u s)
:precision binary32
(*
s
(-
(log
(+
-1.0
(/
1.0
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(/ (- 1.0 u) (+ 1.0 (+ 1.0 (/ PI s)))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + (1.0f / ((u / (1.0f + expf((((float) M_PI) / -s)))) + ((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(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + 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(1.0) + exp((single(pi) / -s)))) + ((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}{1 + e^{\frac{\pi}{-s}}} + \frac{1 - u}{1 + \left(1 + \frac{\pi}{s}\right)}}\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 83.2%
+-commutative83.2%
Simplified83.2%
Final simplification83.2%
(FPCore (u s) :precision binary32 (* s (- (log (+ -1.0 (/ (/ -1.0 u) (+ 0.5 (/ 1.0 (- -1.0 (exp (/ PI (- s))))))))))))
float code(float u, float s) {
return s * -logf((-1.0f + ((-1.0f / u) / (0.5f + (1.0f / (-1.0f - expf((((float) M_PI) / -s))))))));
}
function code(u, s) return Float32(s * Float32(-log(Float32(Float32(-1.0) + Float32(Float32(Float32(-1.0) / u) / Float32(Float32(0.5) + Float32(Float32(1.0) / Float32(Float32(-1.0) - exp(Float32(Float32(pi) / Float32(-s))))))))))) end
function tmp = code(u, s) tmp = s * -log((single(-1.0) + ((single(-1.0) / u) / (single(0.5) + (single(1.0) / (single(-1.0) - exp((single(pi) / -s)))))))); end
\begin{array}{l}
\\
s \cdot \left(-\log \left(-1 + \frac{\frac{-1}{u}}{0.5 + \frac{1}{-1 - e^{\frac{\pi}{-s}}}}\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 8.6%
Taylor expanded in u around -inf 37.2%
associate-/r*37.2%
neg-mul-137.2%
distribute-frac-neg37.2%
Simplified37.2%
Final simplification37.2%
(FPCore (u s) :precision binary32 (* s (* u (- (* -4.0 (/ -1.0 (+ 1.0 (- 1.0 (/ PI s))))) 2.0))))
float code(float u, float s) {
return s * (u * ((-4.0f * (-1.0f / (1.0f + (1.0f - (((float) M_PI) / s))))) - 2.0f));
}
function code(u, s) return Float32(s * Float32(u * Float32(Float32(Float32(-4.0) * Float32(Float32(-1.0) / Float32(Float32(1.0) + Float32(Float32(1.0) - Float32(Float32(pi) / s))))) - Float32(2.0)))) end
function tmp = code(u, s) tmp = s * (u * ((single(-4.0) * (single(-1.0) / (single(1.0) + (single(1.0) - (single(pi) / s))))) - single(2.0))); end
\begin{array}{l}
\\
s \cdot \left(u \cdot \left(-4 \cdot \frac{-1}{1 + \left(1 - \frac{\pi}{s}\right)} - 2\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 8.6%
Taylor expanded in u around 0 8.3%
*-commutative8.3%
associate-*r*8.3%
*-commutative8.3%
sub-neg8.3%
metadata-eval8.3%
distribute-rgt-in8.3%
neg-mul-18.3%
distribute-frac-neg8.3%
metadata-eval8.3%
Simplified8.3%
Taylor expanded in s around inf 16.1%
neg-mul-116.1%
unsub-neg16.1%
Simplified16.1%
Final simplification16.1%
(FPCore (u s) :precision binary32 (* 4.0 (+ (* u (* PI (/ -0.25 u))) (* u (* PI 0.5)))))
float code(float u, float s) {
return 4.0f * ((u * (((float) M_PI) * (-0.25f / u))) + (u * (((float) M_PI) * 0.5f)));
}
function code(u, s) return Float32(Float32(4.0) * Float32(Float32(u * Float32(Float32(pi) * Float32(Float32(-0.25) / u))) + Float32(u * Float32(Float32(pi) * Float32(0.5))))) end
function tmp = code(u, s) tmp = single(4.0) * ((u * (single(pi) * (single(-0.25) / u))) + (u * (single(pi) * single(0.5)))); end
\begin{array}{l}
\\
4 \cdot \left(u \cdot \left(\pi \cdot \frac{-0.25}{u}\right) + u \cdot \left(\pi \cdot 0.5\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 12.4%
Taylor expanded in u around inf 12.4%
associate--l+12.4%
associate-*r/12.4%
*-commutative12.4%
distribute-rgt-out--12.4%
metadata-eval12.4%
Simplified12.4%
distribute-rgt-in12.4%
associate-/l*12.4%
Applied egg-rr12.4%
Final simplification12.4%
(FPCore (u s) :precision binary32 (* 4.0 (* u (* PI (+ 0.5 (/ -0.25 u))))))
float code(float u, float s) {
return 4.0f * (u * (((float) M_PI) * (0.5f + (-0.25f / u))));
}
function code(u, s) return Float32(Float32(4.0) * Float32(u * Float32(Float32(pi) * Float32(Float32(0.5) + Float32(Float32(-0.25) / u))))) end
function tmp = code(u, s) tmp = single(4.0) * (u * (single(pi) * (single(0.5) + (single(-0.25) / u)))); end
\begin{array}{l}
\\
4 \cdot \left(u \cdot \left(\pi \cdot \left(0.5 + \frac{-0.25}{u}\right)\right)\right)
\end{array}
Initial program 99.0%
Simplified99.0%
Taylor expanded in s around inf 12.4%
Taylor expanded in u around inf 12.4%
associate--l+12.4%
associate-*r/12.4%
*-commutative12.4%
distribute-rgt-out--12.4%
metadata-eval12.4%
Simplified12.4%
Taylor expanded in u around inf 12.4%
associate-*r/12.4%
*-commutative12.4%
associate-*r/12.4%
*-commutative12.4%
distribute-lft-out12.4%
Simplified12.4%
Final simplification12.4%
(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 12.4%
associate--r+12.4%
cancel-sign-sub-inv12.4%
cancel-sign-sub-inv12.4%
metadata-eval12.4%
associate-*r*12.4%
distribute-rgt-out12.4%
*-commutative12.4%
metadata-eval12.4%
*-commutative12.4%
associate-*l*12.4%
Simplified12.4%
Taylor expanded in u around 0 12.4%
+-commutative12.4%
associate-*r*12.4%
distribute-rgt-out12.4%
Simplified12.4%
Final simplification12.4%
(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 12.3%
neg-mul-112.3%
Simplified12.3%
Final simplification12.3%
herbie shell --seed 2024076
(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))))