
(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 13 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(-Float32(pi)) / 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 s) (log PI)) (/ s PI))))
float code(float u, float s) {
return s * ((logf(s) - logf(((float) M_PI))) - (s / ((float) M_PI)));
}
function code(u, s) return Float32(s * Float32(Float32(log(s) - log(Float32(pi))) - Float32(s / Float32(pi)))) end
function tmp = code(u, s) tmp = s * ((log(s) - log(single(pi))) - (s / single(pi))); end
\begin{array}{l}
\\
s \cdot \left(\left(\log s - \log \pi\right) - \frac{s}{\pi}\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
associate-*r*24.6%
neg-mul-124.6%
log1p-define24.6%
Simplified24.6%
Taylor expanded in s around 0 24.7%
+-commutative24.7%
mul-1-neg24.7%
unsub-neg24.7%
associate-*r/24.7%
neg-mul-124.7%
mul-1-neg24.7%
unsub-neg24.7%
Simplified24.7%
Final simplification24.7%
(FPCore (u s) :precision binary32 (* s (- (log s) (log PI))))
float code(float u, float s) {
return s * (logf(s) - logf(((float) M_PI)));
}
function code(u, s) return Float32(s * Float32(log(s) - log(Float32(pi)))) end
function tmp = code(u, s) tmp = s * (log(s) - log(single(pi))); end
\begin{array}{l}
\\
s \cdot \left(\log s - \log \pi\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
associate-*r*24.6%
neg-mul-124.6%
log1p-define24.6%
Simplified24.6%
Taylor expanded in s around 0 24.7%
mul-1-neg24.7%
*-commutative24.7%
distribute-rgt-neg-in24.7%
mul-1-neg24.7%
unsub-neg24.7%
Simplified24.7%
Final simplification24.7%
(FPCore (u s) :precision binary32 (* s (- (* -2.0 (* u (/ PI (* s (- -1.0 (/ PI s)))))) (log1p (/ PI s)))))
float code(float u, float s) {
return s * ((-2.0f * (u * (((float) M_PI) / (s * (-1.0f - (((float) M_PI) / s)))))) - log1pf((((float) M_PI) / s)));
}
function code(u, s) return Float32(s * Float32(Float32(Float32(-2.0) * Float32(u * Float32(Float32(pi) / Float32(s * Float32(Float32(-1.0) - Float32(Float32(pi) / s)))))) - log1p(Float32(Float32(pi) / s)))) end
\begin{array}{l}
\\
s \cdot \left(-2 \cdot \left(u \cdot \frac{\pi}{s \cdot \left(-1 - \frac{\pi}{s}\right)}\right) - \mathsf{log1p}\left(\frac{\pi}{s}\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
log1p-define24.6%
associate-/l*24.6%
Simplified24.6%
Final simplification24.6%
(FPCore (u s) :precision binary32 (- (/ (* 2.0 (* u PI)) (+ 1.0 (/ PI s))) (* s (log1p (/ PI s)))))
float code(float u, float s) {
return ((2.0f * (u * ((float) M_PI))) / (1.0f + (((float) M_PI) / s))) - (s * log1pf((((float) M_PI) / s)));
}
function code(u, s) return Float32(Float32(Float32(Float32(2.0) * Float32(u * Float32(pi))) / Float32(Float32(1.0) + Float32(Float32(pi) / s))) - Float32(s * log1p(Float32(Float32(pi) / s)))) end
\begin{array}{l}
\\
\frac{2 \cdot \left(u \cdot \pi\right)}{1 + \frac{\pi}{s}} - s \cdot \mathsf{log1p}\left(\frac{\pi}{s}\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
+-commutative24.6%
mul-1-neg24.6%
unsub-neg24.6%
associate-*r/24.6%
*-commutative24.6%
*-commutative24.6%
log1p-define24.6%
Simplified24.6%
Final simplification24.6%
(FPCore (u s) :precision binary32 (* (- s) (log (+ 1.0 (/ PI s)))))
float code(float u, float s) {
return -s * logf((1.0f + (((float) M_PI) / s)));
}
function code(u, s) return Float32(Float32(-s) * log(Float32(Float32(1.0) + Float32(Float32(pi) / s)))) end
function tmp = code(u, s) tmp = -s * log((single(1.0) + (single(pi) / s))); end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(1 + \frac{\pi}{s}\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
(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(s * Float32(-log1p(Float32(Float32(pi) / s)))) end
\begin{array}{l}
\\
s \cdot \left(-\mathsf{log1p}\left(\frac{\pi}{s}\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
Taylor expanded in u around 0 24.6%
associate-*r*24.6%
neg-mul-124.6%
log1p-define24.6%
Simplified24.6%
Final simplification24.6%
(FPCore (u s) :precision binary32 (* -4.0 (+ (* PI (+ (+ -1.0 (+ 1.0 (* u -0.25))) 0.25)) (* PI (* u -0.25)))))
float code(float u, float s) {
return -4.0f * ((((float) M_PI) * ((-1.0f + (1.0f + (u * -0.25f))) + 0.25f)) + (((float) M_PI) * (u * -0.25f)));
}
function code(u, s) return Float32(Float32(-4.0) * Float32(Float32(Float32(pi) * Float32(Float32(Float32(-1.0) + Float32(Float32(1.0) + Float32(u * Float32(-0.25)))) + Float32(0.25))) + Float32(Float32(pi) * Float32(u * Float32(-0.25))))) end
function tmp = code(u, s) tmp = single(-4.0) * ((single(pi) * ((single(-1.0) + (single(1.0) + (u * single(-0.25)))) + single(0.25))) + (single(pi) * (u * single(-0.25)))); end
\begin{array}{l}
\\
-4 \cdot \left(\pi \cdot \left(\left(-1 + \left(1 + u \cdot -0.25\right)\right) + 0.25\right) + \pi \cdot \left(u \cdot -0.25\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around -inf 11.2%
associate--r+11.2%
cancel-sign-sub-inv11.2%
cancel-sign-sub-inv11.2%
metadata-eval11.2%
associate-*r*11.2%
distribute-rgt-out11.2%
metadata-eval11.2%
*-commutative11.2%
*-commutative11.2%
associate-*l*11.2%
Simplified11.2%
expm1-log1p-u11.2%
expm1-undefine11.2%
*-commutative11.2%
Applied egg-rr11.2%
sub-neg11.2%
log1p-undefine11.2%
rem-exp-log11.2%
metadata-eval11.2%
Applied egg-rr11.2%
Final simplification11.2%
(FPCore (u s) :precision binary32 (+ -1.0 (- 1.0 (* -4.0 (+ (* PI -0.25) (* 0.5 (* u PI)))))))
float code(float u, float s) {
return -1.0f + (1.0f - (-4.0f * ((((float) M_PI) * -0.25f) + (0.5f * (u * ((float) M_PI))))));
}
function code(u, s) return Float32(Float32(-1.0) + Float32(Float32(1.0) - 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(-1.0) + (single(1.0) - (single(-4.0) * ((single(pi) * single(-0.25)) + (single(0.5) * (u * single(pi)))))); end
\begin{array}{l}
\\
-1 + \left(1 - -4 \cdot \left(\pi \cdot -0.25 + 0.5 \cdot \left(u \cdot \pi\right)\right)\right)
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
expm1-log1p-u23.8%
expm1-undefine13.7%
+-commutative13.7%
fma-define13.7%
associate-*l*13.7%
Applied egg-rr13.7%
sub-neg13.7%
log1p-undefine13.7%
rem-exp-log14.0%
distribute-lft-neg-in14.0%
unsub-neg14.0%
metadata-eval14.0%
Simplified14.0%
Taylor expanded in s around inf 11.2%
Final simplification11.2%
(FPCore (u s) :precision binary32 (if (<= s 1.0999999780167719e-18) 0.0 (* s (/ (- PI) s))))
float code(float u, float s) {
float tmp;
if (s <= 1.0999999780167719e-18f) {
tmp = 0.0f;
} else {
tmp = s * (-((float) M_PI) / s);
}
return tmp;
}
function code(u, s) tmp = Float32(0.0) if (s <= Float32(1.0999999780167719e-18)) tmp = Float32(0.0); else tmp = Float32(s * Float32(Float32(-Float32(pi)) / s)); end return tmp end
function tmp_2 = code(u, s) tmp = single(0.0); if (s <= single(1.0999999780167719e-18)) tmp = single(0.0); else tmp = s * (-single(pi) / s); end tmp_2 = tmp; end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;s \leq 1.0999999780167719 \cdot 10^{-18}:\\
\;\;\;\;0\\
\mathbf{else}:\\
\;\;\;\;s \cdot \frac{-\pi}{s}\\
\end{array}
\end{array}
if s < 1.09999998e-18Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 22.0%
+-commutative22.0%
fma-define22.0%
Simplified22.0%
expm1-log1p-u21.9%
expm1-undefine11.9%
+-commutative11.9%
fma-define11.9%
associate-*l*11.9%
Applied egg-rr11.9%
sub-neg11.9%
log1p-undefine11.9%
rem-exp-log11.9%
distribute-lft-neg-in11.9%
unsub-neg11.9%
metadata-eval11.9%
Simplified11.9%
Taylor expanded in s around 0 13.3%
metadata-eval13.3%
Applied egg-rr13.3%
if 1.09999998e-18 < s Initial program 98.8%
Simplified98.8%
Taylor expanded in u around 0 15.1%
Final simplification14.1%
(FPCore (u s) :precision binary32 (if (<= s 1.0999999780167719e-18) 0.0 (- PI)))
float code(float u, float s) {
float tmp;
if (s <= 1.0999999780167719e-18f) {
tmp = 0.0f;
} else {
tmp = -((float) M_PI);
}
return tmp;
}
function code(u, s) tmp = Float32(0.0) if (s <= Float32(1.0999999780167719e-18)) tmp = Float32(0.0); else tmp = Float32(-Float32(pi)); end return tmp end
function tmp_2 = code(u, s) tmp = single(0.0); if (s <= single(1.0999999780167719e-18)) tmp = single(0.0); else tmp = -single(pi); end tmp_2 = tmp; end
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;s \leq 1.0999999780167719 \cdot 10^{-18}:\\
\;\;\;\;0\\
\mathbf{else}:\\
\;\;\;\;-\pi\\
\end{array}
\end{array}
if s < 1.09999998e-18Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 22.0%
+-commutative22.0%
fma-define22.0%
Simplified22.0%
expm1-log1p-u21.9%
expm1-undefine11.9%
+-commutative11.9%
fma-define11.9%
associate-*l*11.9%
Applied egg-rr11.9%
sub-neg11.9%
log1p-undefine11.9%
rem-exp-log11.9%
distribute-lft-neg-in11.9%
unsub-neg11.9%
metadata-eval11.9%
Simplified11.9%
Taylor expanded in s around 0 13.3%
metadata-eval13.3%
Applied egg-rr13.3%
if 1.09999998e-18 < s Initial program 98.8%
Simplified98.8%
Taylor expanded in u around 0 15.1%
neg-mul-115.1%
Simplified15.1%
(FPCore (u s) :precision binary32 (- (* PI (* u 2.0)) PI))
float code(float u, float s) {
return (((float) M_PI) * (u * 2.0f)) - ((float) M_PI);
}
function code(u, s) return Float32(Float32(Float32(pi) * Float32(u * Float32(2.0))) - Float32(pi)) end
function tmp = code(u, s) tmp = (single(pi) * (u * single(2.0))) - single(pi); end
\begin{array}{l}
\\
\pi \cdot \left(u \cdot 2\right) - \pi
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around -inf 11.2%
associate--r+11.2%
cancel-sign-sub-inv11.2%
cancel-sign-sub-inv11.2%
metadata-eval11.2%
associate-*r*11.2%
distribute-rgt-out11.2%
metadata-eval11.2%
*-commutative11.2%
*-commutative11.2%
associate-*l*11.2%
Simplified11.2%
Taylor expanded in u around inf 11.2%
Taylor expanded in u around 0 11.2%
+-commutative11.2%
mul-1-neg11.2%
unsub-neg11.2%
associate-*r*11.2%
Simplified11.2%
Final simplification11.2%
(FPCore (u s) :precision binary32 0.0)
float code(float u, float s) {
return 0.0f;
}
real(4) function code(u, s)
real(4), intent (in) :: u
real(4), intent (in) :: s
code = 0.0e0
end function
function code(u, s) return Float32(0.0) end
function tmp = code(u, s) tmp = single(0.0); end
\begin{array}{l}
\\
0
\end{array}
Initial program 98.8%
Simplified98.8%
Taylor expanded in s around inf 24.1%
+-commutative24.1%
fma-define24.1%
Simplified24.1%
expm1-log1p-u23.8%
expm1-undefine13.7%
+-commutative13.7%
fma-define13.7%
associate-*l*13.7%
Applied egg-rr13.7%
sub-neg13.7%
log1p-undefine13.7%
rem-exp-log14.0%
distribute-lft-neg-in14.0%
unsub-neg14.0%
metadata-eval14.0%
Simplified14.0%
Taylor expanded in s around 0 10.7%
metadata-eval10.7%
Applied egg-rr10.7%
herbie shell --seed 2024123
(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))))