
(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 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)))))\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 (+ (exp (/ (PI) s)) 1.0))))
(*
(- s)
(log
(-
(/ 1.0 (fma (- (/ 1.0 (+ (exp (/ (- (PI)) s)) 1.0)) t_0) u t_0))
1.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}\\
\left(-s\right) \cdot \log \left(\frac{1}{\mathsf{fma}\left(\frac{1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1} - t\_0, u, t\_0\right)} - 1\right)
\end{array}
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites98.9%
(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 98.9%
Taylor expanded in u around inf
*-commutativeN/A
lower-*.f32N/A
Applied rewrites97.5%
(FPCore (u s) :precision binary32 (let* ((t_0 (/ 1.0 (+ (exp (/ (PI) s)) 1.0)))) (* (- s) (log (- (/ 1.0 (fma (- 0.5 t_0) u t_0)) 1.0)))))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}\\
\left(-s\right) \cdot \log \left(\frac{1}{\mathsf{fma}\left(0.5 - t\_0, u, t\_0\right)} - 1\right)
\end{array}
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites98.9%
Taylor expanded in s around inf
Applied rewrites37.2%
(FPCore (u s)
:precision binary32
(let* ((t_0 (* 0.5 (PI))) (t_1 (* t_0 -1.0)) (t_2 (fma t_1 u (* t_0 0.5))))
(*
(- s)
(log
(fma
(/
(-
(/ (fma (/ (PI) 0.125) 0.5 (/ (fma t_1 u (* 2.0 t_2)) 0.0625)) 7.0)
(*
(fma (/ (PI) 0.5) 0.5 (fma (/ t_2 0.125) 2.0 (/ (* t_1 u) 0.25)))
0.14285714285714285))
(- s))
-1.0
1.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := 0.5 \cdot \mathsf{PI}\left(\right)\\
t_1 := t\_0 \cdot -1\\
t_2 := \mathsf{fma}\left(t\_1, u, t\_0 \cdot 0.5\right)\\
\left(-s\right) \cdot \log \left(\mathsf{fma}\left(\frac{\frac{\mathsf{fma}\left(\frac{\mathsf{PI}\left(\right)}{0.125}, 0.5, \frac{\mathsf{fma}\left(t\_1, u, 2 \cdot t\_2\right)}{0.0625}\right)}{7} - \mathsf{fma}\left(\frac{\mathsf{PI}\left(\right)}{0.5}, 0.5, \mathsf{fma}\left(\frac{t\_2}{0.125}, 2, \frac{t\_1 \cdot u}{0.25}\right)\right) \cdot 0.14285714285714285}{-s}, -1, 1\right)\right)
\end{array}
\end{array}
Initial program 98.9%
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%
Applied rewrites98.9%
Taylor expanded in s around -inf
Applied rewrites24.7%
Final simplification24.7%
(FPCore (u s) :precision binary32 (* (- s) (log (fma (/ (fma (* 0.5 (PI)) u (* -0.25 (PI))) s) -4.0 1.0))))
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\mathsf{fma}\left(\frac{\mathsf{fma}\left(0.5 \cdot \mathsf{PI}\left(\right), u, -0.25 \cdot \mathsf{PI}\left(\right)\right)}{s}, -4, 1\right)\right)
\end{array}
Initial program 98.9%
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
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites24.7%
(FPCore (u s) :precision binary32 (* (- s) (log (fma (/ (fma 0.5 (* (PI) u) (* -0.25 (PI))) s) -4.0 1.0))))
\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\mathsf{fma}\left(\frac{\mathsf{fma}\left(0.5, \mathsf{PI}\left(\right) \cdot u, -0.25 \cdot \mathsf{PI}\left(\right)\right)}{s}, -4, 1\right)\right)
\end{array}
Initial program 98.9%
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
lower--.f32N/A
Applied rewrites14.8%
Taylor expanded in s around inf
Applied rewrites24.7%
(FPCore (u s) :precision binary32 (let* ((t_0 (sqrt (PI)))) (* (fma (* (* 0.5 u) t_0) t_0 (* -0.25 (PI))) 4.0)))
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{PI}\left(\right)}\\
\mathsf{fma}\left(\left(0.5 \cdot u\right) \cdot t\_0, t\_0, -0.25 \cdot \mathsf{PI}\left(\right)\right) \cdot 4
\end{array}
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.4
Applied rewrites11.4%
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.f3211.7
Applied rewrites11.7%
Applied rewrites11.7%
(FPCore (u s) :precision binary32 (* (* (PI) (fma 0.5 u -0.25)) 4.0))
\begin{array}{l}
\\
\left(\mathsf{PI}\left(\right) \cdot \mathsf{fma}\left(0.5, u, -0.25\right)\right) \cdot 4
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.4
Applied rewrites11.4%
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.f3211.7
Applied rewrites11.7%
Applied rewrites11.7%
(FPCore (u s) :precision binary32 (fma (* (PI) u) 2.0 (- (PI))))
\begin{array}{l}
\\
\mathsf{fma}\left(\mathsf{PI}\left(\right) \cdot u, 2, -\mathsf{PI}\left(\right)\right)
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.4
Applied rewrites11.4%
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.f3211.7
Applied rewrites11.7%
Taylor expanded in u around 0
Applied rewrites11.7%
(FPCore (u s) :precision binary32 (- (PI)))
\begin{array}{l}
\\
-\mathsf{PI}\left(\right)
\end{array}
Initial program 98.9%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.4
Applied rewrites11.4%
herbie shell --seed 2024364
(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))))