
(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)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\mathsf{PI}\left(\right)}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\mathsf{PI}\left(\right)}{s}}} - t\_0\right) + t\_0} - 1\right)
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 8 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)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\mathsf{PI}\left(\right)}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\mathsf{PI}\left(\right)}{s}}} - t\_0\right) + t\_0} - 1\right)
\end{array}
\end{array}
(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)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{1 + e^{\frac{\mathsf{PI}\left(\right)}{s}}}\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\mathsf{PI}\left(\right)}{s}}} - t\_0\right) + t\_0} - 1\right)
\end{array}
\end{array}
Initial program 99.0%
(FPCore (u s)
:precision binary32
(*
(- s)
(log
(-
(/
(/ 1.0 u)
(- (/ 1.0 (+ (exp (/ (- (PI)) s)) 1.0)) (/ 1.0 (+ (exp (/ (PI) s)) 1.0))))
1.0))))\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\frac{\frac{1}{u}}{\frac{1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1} - \frac{1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}} - 1\right)
\end{array}
Initial program 99.0%
Taylor expanded in u around inf
lower--.f32N/A
Applied rewrites97.0%
(FPCore (u s)
:precision binary32
(*
(- s)
(log
(-
(/
1.0
(*
(- (/ 1.0 (+ (exp (/ (- (PI)) s)) 1.0)) (/ 1.0 (+ (exp (/ (PI) s)) 1.0)))
u))
1.0))))\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\frac{1}{\left(\frac{1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1} - \frac{1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}\right) \cdot u} - 1\right)
\end{array}
Initial program 99.0%
Taylor expanded in u around inf
*-commutativeN/A
lower-*.f32N/A
Applied rewrites97.0%
(FPCore (u s)
:precision binary32
(let* ((t_0 (* 0.25 (PI))))
(if (<= s 3.5000000480067683e-6)
(* (- s) (log (fma (/ (fma (* -0.5 (PI)) u t_0) s) 4.0 1.0)))
(* (- s) (* (- t_0 (* 0.5 (* u (PI)))) (/ 4.0 s))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := 0.25 \cdot \mathsf{PI}\left(\right)\\
\mathbf{if}\;s \leq 3.5000000480067683 \cdot 10^{-6}:\\
\;\;\;\;\left(-s\right) \cdot \log \left(\mathsf{fma}\left(\frac{\mathsf{fma}\left(-0.5 \cdot \mathsf{PI}\left(\right), u, t\_0\right)}{s}, 4, 1\right)\right)\\
\mathbf{else}:\\
\;\;\;\;\left(-s\right) \cdot \left(\left(t\_0 - 0.5 \cdot \left(u \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \frac{4}{s}\right)\\
\end{array}
\end{array}
if s < 3.50000005e-6Initial program 99.0%
Taylor expanded in u around inf
*-commutativeN/A
lower-*.f32N/A
Applied rewrites99.0%
Taylor expanded in s around -inf
associate-*r/N/A
+-commutativeN/A
associate-*r/N/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites10.8%
if 3.50000005e-6 < s Initial program 98.6%
Taylor expanded in s around -inf
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f32N/A
fp-cancel-sub-sign-invN/A
distribute-rgt-out--N/A
metadata-evalN/A
associate-*r*N/A
metadata-evalN/A
lower-fma.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-/.f3223.3
Applied rewrites23.2%
Applied rewrites25.0%
(FPCore (u s) :precision binary32 (* (- s) (/ (fma 0.0 -0.5 (* (* (PI) (fabs (* -0.5 u))) -4.0)) (- s))))
\begin{array}{l}
\\
\left(-s\right) \cdot \frac{\mathsf{fma}\left(0, -0.5, \left(\mathsf{PI}\left(\right) \cdot \left|-0.5 \cdot u\right|\right) \cdot -4\right)}{-s}
\end{array}
Initial program 99.0%
Taylor expanded in s around -inf
Applied rewrites7.3%
Applied rewrites11.5%
Applied rewrites11.5%
Taylor expanded in u around inf
Applied rewrites12.1%
Final simplification12.1%
(FPCore (u s) :precision binary32 (* (- s) (* (- (* 0.25 (PI)) (* 0.5 (* u (PI)))) (/ 4.0 s))))
\begin{array}{l}
\\
\left(-s\right) \cdot \left(\left(0.25 \cdot \mathsf{PI}\left(\right) - 0.5 \cdot \left(u \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \frac{4}{s}\right)
\end{array}
Initial program 99.0%
Taylor expanded in s around -inf
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
lower-*.f32N/A
fp-cancel-sub-sign-invN/A
distribute-rgt-out--N/A
metadata-evalN/A
associate-*r*N/A
metadata-evalN/A
lower-fma.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-/.f3211.5
Applied rewrites11.5%
Applied rewrites11.9%
(FPCore (u s) :precision binary32 (* (fma (* -0.5 (PI)) u (* 0.25 (PI))) -4.0))
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5 \cdot \mathsf{PI}\left(\right), u, 0.25 \cdot \mathsf{PI}\left(\right)\right) \cdot -4
\end{array}
Initial program 99.0%
lift-/.f32N/A
lift-PI.f32N/A
add-cube-cbrtN/A
associate-/l*N/A
lower-*.f32N/A
pow2N/A
lower-pow.f32N/A
lift-PI.f32N/A
lower-cbrt.f32N/A
lower-/.f32N/A
lift-PI.f32N/A
lower-cbrt.f3298.9
Applied rewrites98.9%
Taylor expanded in s around -inf
*-commutativeN/A
lower-*.f32N/A
fp-cancel-sub-sign-invN/A
*-commutativeN/A
distribute-rgt-out--N/A
metadata-evalN/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f32N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-*.f32N/A
lower-PI.f3211.6
Applied rewrites11.5%
Final simplification11.6%
(FPCore (u s) :precision binary32 (- (PI)))
\begin{array}{l}
\\
-\mathsf{PI}\left(\right)
\end{array}
Initial program 99.0%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.6
Applied rewrites11.6%
herbie shell --seed 2024326
(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))))