
(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
(let* ((t_0 (exp (/ PI s)))
(t_1
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(+ (/ 1.0 (+ 1.0 t_0)) (/ u (- -1.0 t_0))))))
(* s (log (/ (+ 1.0 (/ 1.0 t_1)) (+ -1.0 (pow t_1 -2.0)))))))
float code(float u, float s) {
float t_0 = expf((((float) M_PI) / s));
float t_1 = (u / (1.0f + expf((((float) M_PI) / -s)))) + ((1.0f / (1.0f + t_0)) + (u / (-1.0f - t_0)));
return s * logf(((1.0f + (1.0f / t_1)) / (-1.0f + powf(t_1, -2.0f))));
}
function code(u, s) t_0 = exp(Float32(Float32(pi) / s)) t_1 = Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + t_0)) + Float32(u / Float32(Float32(-1.0) - t_0)))) return Float32(s * log(Float32(Float32(Float32(1.0) + Float32(Float32(1.0) / t_1)) / Float32(Float32(-1.0) + (t_1 ^ Float32(-2.0)))))) end
function tmp = code(u, s) t_0 = exp((single(pi) / s)); t_1 = (u / (single(1.0) + exp((single(pi) / -s)))) + ((single(1.0) / (single(1.0) + t_0)) + (u / (single(-1.0) - t_0))); tmp = s * log(((single(1.0) + (single(1.0) / t_1)) / (single(-1.0) + (t_1 ^ single(-2.0))))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{\pi}{s}}\\
t_1 := \frac{u}{1 + e^{\frac{\pi}{-s}}} + \left(\frac{1}{1 + t\_0} + \frac{u}{-1 - t\_0}\right)\\
s \cdot \log \left(\frac{1 + \frac{1}{t\_1}}{-1 + {t\_1}^{-2}}\right)
\end{array}
\end{array}
Initial program 99.0%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
Applied rewrites99.1%
lift-/.f32N/A
clear-numN/A
associate-/r/N/A
Applied rewrites99.0%
lift-*.f32N/A
*-commutativeN/A
lift-/.f32N/A
Applied rewrites99.1%
Final simplification99.1%
(FPCore (u s)
:precision binary32
(*
(- s)
(log
(+
-1.0
(/
1.0
(+
(*
u
(+ (/ 1.0 (+ 1.0 (exp (/ PI (- s))))) (/ 1.0 (- -1.0 (exp (/ PI s))))))
(/ 1.0 (+ 1.0 (exp (* PI (/ 1.0 s)))))))))))
float code(float u, float s) {
return -s * logf((-1.0f + (1.0f / ((u * ((1.0f / (1.0f + expf((((float) M_PI) / -s)))) + (1.0f / (-1.0f - expf((((float) M_PI) / s)))))) + (1.0f / (1.0f + expf((((float) M_PI) * (1.0f / s)))))))));
}
function code(u, s) return Float32(Float32(-s) * log(Float32(Float32(-1.0) + Float32(Float32(1.0) / Float32(Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(1.0) / Float32(Float32(-1.0) - exp(Float32(Float32(pi) / s)))))) + Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) * Float32(Float32(1.0) / s)))))))))) end
function tmp = code(u, s) tmp = -s * log((single(-1.0) + (single(1.0) / ((u * ((single(1.0) / (single(1.0) + exp((single(pi) / -s)))) + (single(1.0) / (single(-1.0) - exp((single(pi) / s)))))) + (single(1.0) / (single(1.0) + exp((single(pi) * (single(1.0) / s))))))))); end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(-1 + \frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{\pi}{-s}}} + \frac{1}{-1 - e^{\frac{\pi}{s}}}\right) + \frac{1}{1 + e^{\pi \cdot \frac{1}{s}}}}\right)
\end{array}
Initial program 99.0%
lift-/.f32N/A
clear-numN/A
associate-/r/N/A
lower-*.f32N/A
lower-/.f3299.0
Applied rewrites99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(let* ((t_0 (exp (/ PI s))))
(*
(- s)
(log
(+
-1.0
(/
1.0
(+
(/ u (+ 1.0 (exp (/ PI (- s)))))
(+ (/ 1.0 (+ 1.0 t_0)) (/ u (- -1.0 t_0))))))))))
float code(float u, float s) {
float t_0 = expf((((float) M_PI) / s));
return -s * logf((-1.0f + (1.0f / ((u / (1.0f + expf((((float) M_PI) / -s)))) + ((1.0f / (1.0f + t_0)) + (u / (-1.0f - t_0)))))));
}
function code(u, s) t_0 = exp(Float32(Float32(pi) / s)) return Float32(Float32(-s) * 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) / Float32(Float32(1.0) + t_0)) + Float32(u / Float32(Float32(-1.0) - t_0)))))))) end
function tmp = code(u, s) t_0 = exp((single(pi) / s)); tmp = -s * log((single(-1.0) + (single(1.0) / ((u / (single(1.0) + exp((single(pi) / -s)))) + ((single(1.0) / (single(1.0) + t_0)) + (u / (single(-1.0) - t_0))))))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{\pi}{s}}\\
\left(-s\right) \cdot \log \left(-1 + \frac{1}{\frac{u}{1 + e^{\frac{\pi}{-s}}} + \left(\frac{1}{1 + t\_0} + \frac{u}{-1 - t\_0}\right)}\right)
\end{array}
\end{array}
Initial program 99.0%
lift-log.f32N/A
lift--.f32N/A
flip--N/A
Applied rewrites99.1%
lift-/.f32N/A
clear-numN/A
associate-/r/N/A
Applied rewrites99.0%
lift-neg.f32N/A
Applied rewrites99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(let* ((t_0 (exp (/ PI s))))
(*
(- s)
(log
(+
-1.0
(/
1.0
(+
(+ (/ u (+ 1.0 (exp (/ PI (- s))))) (/ 1.0 (+ 1.0 t_0)))
(/ u (- -1.0 t_0)))))))))
float code(float u, float s) {
float t_0 = expf((((float) M_PI) / s));
return -s * logf((-1.0f + (1.0f / (((u / (1.0f + expf((((float) M_PI) / -s)))) + (1.0f / (1.0f + t_0))) + (u / (-1.0f - t_0))))));
}
function code(u, s) t_0 = exp(Float32(Float32(pi) / s)) return Float32(Float32(-s) * log(Float32(Float32(-1.0) + Float32(Float32(1.0) / Float32(Float32(Float32(u / Float32(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(1.0) / Float32(Float32(1.0) + t_0))) + Float32(u / Float32(Float32(-1.0) - t_0))))))) end
function tmp = code(u, s) t_0 = exp((single(pi) / s)); tmp = -s * log((single(-1.0) + (single(1.0) / (((u / (single(1.0) + exp((single(pi) / -s)))) + (single(1.0) / (single(1.0) + t_0))) + (u / (single(-1.0) - t_0)))))); end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{\pi}{s}}\\
\left(-s\right) \cdot \log \left(-1 + \frac{1}{\left(\frac{u}{1 + e^{\frac{\pi}{-s}}} + \frac{1}{1 + t\_0}\right) + \frac{u}{-1 - t\_0}}\right)
\end{array}
\end{array}
Initial program 99.0%
lift-neg.f32N/A
neg-sub0N/A
sub-negN/A
lift-neg.f32N/A
flip3-+N/A
lower-/.f32N/A
metadata-evalN/A
lower-+.f32N/A
lower-pow.f32N/A
metadata-evalN/A
lower-+.f32N/A
lower--.f32N/A
lower-*.f32N/A
lower-*.f3240.3
Applied rewrites40.3%
lift-+.f32N/A
lift-*.f32N/A
lower-fma.f3240.3
Applied rewrites40.3%
Taylor expanded in s around 0
associate-*r*N/A
lower-*.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-log.f32N/A
sub-negN/A
metadata-evalN/A
Applied rewrites99.0%
Final simplification99.0%
(FPCore (u s)
:precision binary32
(*
(- s)
(log
(+
-1.0
(/
1.0
(*
u
(+
(/ 1.0 (+ 1.0 (exp (/ PI (- s)))))
(/ 1.0 (- -1.0 (exp (/ PI s)))))))))))
float code(float u, float s) {
return -s * logf((-1.0f + (1.0f / (u * ((1.0f / (1.0f + expf((((float) M_PI) / -s)))) + (1.0f / (-1.0f - expf((((float) M_PI) / s)))))))));
}
function code(u, s) return Float32(Float32(-s) * log(Float32(Float32(-1.0) + Float32(Float32(1.0) / Float32(u * Float32(Float32(Float32(1.0) / Float32(Float32(1.0) + exp(Float32(Float32(pi) / Float32(-s))))) + Float32(Float32(1.0) / 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) / (single(1.0) + exp((single(pi) / -s)))) + (single(1.0) / (single(-1.0) - exp((single(pi) / s))))))))); end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(-1 + \frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{\pi}{-s}}} + \frac{1}{-1 - e^{\frac{\pi}{s}}}\right)}\right)
\end{array}
Initial program 99.0%
Taylor expanded in u around inf
lower-*.f32N/A
sub-negN/A
lower-+.f32N/A
lower-/.f32N/A
lower-+.f32N/A
lower-exp.f32N/A
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f32N/A
lower-PI.f32N/A
mul-1-negN/A
lower-neg.f32N/A
distribute-neg-fracN/A
Applied rewrites97.1%
Final simplification97.1%
(FPCore (u s) :precision binary32 (* (- s) (log (fma (/ (fma u (* PI -0.5) (* PI 0.25)) s) 4.0 1.0))))
float code(float u, float s) {
return -s * logf(fmaf((fmaf(u, (((float) M_PI) * -0.5f), (((float) M_PI) * 0.25f)) / s), 4.0f, 1.0f));
}
function code(u, s) return Float32(Float32(-s) * log(fma(Float32(fma(u, Float32(Float32(pi) * Float32(-0.5)), Float32(Float32(pi) * Float32(0.25))) / s), Float32(4.0), Float32(1.0)))) end
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\mathsf{fma}\left(\frac{\mathsf{fma}\left(u, \pi \cdot -0.5, \pi \cdot 0.25\right)}{s}, 4, 1\right)\right)
\end{array}
Initial program 99.0%
Taylor expanded in s around inf
Applied rewrites9.9%
Taylor expanded in s around -inf
associate-*r/N/A
+-commutativeN/A
associate-*r/N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites25.3%
(FPCore (u s) :precision binary32 (let* ((t_0 (fma PI -0.25 (* 0.5 (* u PI))))) (/ (fma -0.5 (* 0.0 (* t_0 t_0)) (* 4.0 (* s t_0))) s)))
float code(float u, float s) {
float t_0 = fmaf(((float) M_PI), -0.25f, (0.5f * (u * ((float) M_PI))));
return fmaf(-0.5f, (0.0f * (t_0 * t_0)), (4.0f * (s * t_0))) / s;
}
function code(u, s) t_0 = fma(Float32(pi), Float32(-0.25), Float32(Float32(0.5) * Float32(u * Float32(pi)))) return Float32(fma(Float32(-0.5), Float32(Float32(0.0) * Float32(t_0 * t_0)), Float32(Float32(4.0) * Float32(s * t_0))) / s) end
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{fma}\left(\pi, -0.25, 0.5 \cdot \left(u \cdot \pi\right)\right)\\
\frac{\mathsf{fma}\left(-0.5, 0 \cdot \left(t\_0 \cdot t\_0\right), 4 \cdot \left(s \cdot t\_0\right)\right)}{s}
\end{array}
\end{array}
Initial program 99.0%
Taylor expanded in s around inf
Applied rewrites9.2%
Taylor expanded in s around 0
Applied rewrites12.2%
Final simplification12.2%
(FPCore (u s) :precision binary32 (* 4.0 (fma PI (* u 0.5) (* PI -0.25))))
float code(float u, float s) {
return 4.0f * fmaf(((float) M_PI), (u * 0.5f), (((float) M_PI) * -0.25f));
}
function code(u, s) return Float32(Float32(4.0) * fma(Float32(pi), Float32(u * Float32(0.5)), Float32(Float32(pi) * Float32(-0.25)))) end
\begin{array}{l}
\\
4 \cdot \mathsf{fma}\left(\pi, u \cdot 0.5, \pi \cdot -0.25\right)
\end{array}
Initial program 99.0%
Taylor expanded in s around inf
lower-*.f32N/A
cancel-sign-sub-invN/A
metadata-evalN/A
*-commutativeN/A
distribute-rgt-out--N/A
metadata-evalN/A
associate-*l*N/A
lower-fma.f32N/A
lower-PI.f32N/A
*-commutativeN/A
lower-*.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f3212.2
Applied rewrites12.2%
(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%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3212.0
Applied rewrites12.0%
(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 99.0%
lift-neg.f32N/A
neg-sub0N/A
sub-negN/A
lift-neg.f32N/A
flip3-+N/A
lower-/.f32N/A
metadata-evalN/A
lower-+.f32N/A
lower-pow.f32N/A
metadata-evalN/A
lower-+.f32N/A
lower--.f32N/A
lower-*.f32N/A
lower-*.f3240.3
Applied rewrites40.3%
lift-+.f32N/A
lift-*.f32N/A
lower-fma.f3240.3
Applied rewrites40.3%
Taylor expanded in s around inf
mul-1-negN/A
distribute-rgt-neg-inN/A
distribute-rgt-outN/A
metadata-evalN/A
mul0-rgtN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-*.f329.9
Applied rewrites9.9%
Taylor expanded in s around 0
Applied rewrites9.9%
herbie shell --seed 2024231
(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))))