
(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 (exp (/ (PI) s)))
(t_1 (exp (- (log1p t_0))))
(t_2 (* (- (exp (- (log1p (exp (/ (- (PI)) s))))) t_1) u)))
(*
(- s)
(log
(-
(/ 1.0 (/ (- (pow (- t_0 -1.0) -2.0) (pow t_2 2.0)) (- t_1 t_2)))
1.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := e^{\frac{\mathsf{PI}\left(\right)}{s}}\\
t_1 := e^{-\mathsf{log1p}\left(t\_0\right)}\\
t_2 := \left(e^{-\mathsf{log1p}\left(e^{\frac{-\mathsf{PI}\left(\right)}{s}}\right)} - t\_1\right) \cdot u\\
\left(-s\right) \cdot \log \left(\frac{1}{\frac{{\left(t\_0 - -1\right)}^{-2} - {t\_2}^{2}}{t\_1 - t\_2}} - 1\right)
\end{array}
\end{array}
Initial program 99.1%
Applied rewrites99.1%
(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 99.1%
Taylor expanded in u around 0
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites99.1%
Final simplification99.1%
(FPCore (u s)
:precision binary32
(*
(- s)
(log
(-
(/
1.0
(*
u
(-
(/ 1.0 (+ 1.0 (exp (/ (- (PI)) s))))
(/ 1.0 (+ 1.0 (exp (/ (PI) s)))))))
1.0))))\begin{array}{l}
\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{-\mathsf{PI}\left(\right)}{s}}} - \frac{1}{1 + e^{\frac{\mathsf{PI}\left(\right)}{s}}}\right)} - 1\right)
\end{array}
Initial program 99.1%
Taylor expanded in s around inf
lower-/.f32N/A
distribute-rgt-out--N/A
metadata-evalN/A
lower-*.f32N/A
lower-PI.f323.3
Applied rewrites3.3%
Taylor expanded in u around inf
lower-/.f32N/A
lower-*.f32N/A
lower--.f32N/A
lower-/.f32N/A
lower-+.f32N/A
lower-exp.f32N/A
associate-*r/N/A
lower-/.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f32N/A
lower-/.f32N/A
lower-+.f32N/A
Applied rewrites98.1%
(FPCore (u s)
:precision binary32
(let* ((t_0 (- (PI))) (t_1 (* (PI) (PI))))
(*
(- s)
(log
(-
(/
1.0
(+
(*
u
(-
(/ 1.0 (+ 1.0 (exp (/ t_0 s))))
(/ 1.0 (+ 1.0 (+ 1.0 (fma 0.5 (/ t_1 (* s s)) (/ (PI) s)))))))
(/ 1.0 (fma (/ (fma (/ t_1 s) -0.5 t_0) s) -1.0 2.0))))
1.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\mathsf{PI}\left(\right)\\
t_1 := \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{t\_0}{s}}} - \frac{1}{1 + \left(1 + \mathsf{fma}\left(0.5, \frac{t\_1}{s \cdot s}, \frac{\mathsf{PI}\left(\right)}{s}\right)\right)}\right) + \frac{1}{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{t\_1}{s}, -0.5, t\_0\right)}{s}, -1, 2\right)}} - 1\right)
\end{array}
\end{array}
Initial program 99.1%
Taylor expanded in s around -inf
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3294.5
Applied rewrites94.5%
Taylor expanded in s around inf
lower-+.f32N/A
lower-fma.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
unpow2N/A
lower-*.f32N/A
lower-/.f32N/A
lower-PI.f3294.5
Applied rewrites94.5%
(FPCore (u s)
:precision binary32
(let* ((t_0 (- (PI))))
(*
(- s)
(log
(-
(/
1.0
(+
(*
u
(-
(/ 1.0 (+ 1.0 (exp (/ t_0 s))))
(/ 1.0 (+ 1.0 (+ 1.0 (/ (PI) s))))))
(/ 1.0 (fma (/ (fma (/ (* (PI) (PI)) s) -0.5 t_0) s) -1.0 2.0))))
1.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\mathsf{PI}\left(\right)\\
\left(-s\right) \cdot \log \left(\frac{1}{u \cdot \left(\frac{1}{1 + e^{\frac{t\_0}{s}}} - \frac{1}{1 + \left(1 + \frac{\mathsf{PI}\left(\right)}{s}\right)}\right) + \frac{1}{\mathsf{fma}\left(\frac{\mathsf{fma}\left(\frac{\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)}{s}, -0.5, t\_0\right)}{s}, -1, 2\right)}} - 1\right)
\end{array}
\end{array}
Initial program 99.1%
Taylor expanded in s around -inf
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
lower-/.f32N/A
unpow2N/A
lower-*.f32N/A
lower-PI.f32N/A
lower-PI.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3294.5
Applied rewrites94.5%
Taylor expanded in s around inf
lower-+.f32N/A
lower-/.f32N/A
lower-PI.f3294.0
Applied rewrites94.0%
(FPCore (u s) :precision binary32 (* (- s) (log (fma (/ (fma (* (PI) 0.5) 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(\mathsf{PI}\left(\right) \cdot 0.5, u, -0.25 \cdot \mathsf{PI}\left(\right)\right)}{s}, -4, 1\right)\right)
\end{array}
Initial program 99.1%
Taylor expanded in s around inf
+-commutativeN/A
*-commutativeN/A
lower-fma.f32N/A
Applied rewrites24.7%
(FPCore (u s) :precision binary32 (fma -1.0 (PI) (* 2.0 (* u (PI)))))
\begin{array}{l}
\\
\mathsf{fma}\left(-1, \mathsf{PI}\left(\right), 2 \cdot \left(u \cdot \mathsf{PI}\left(\right)\right)\right)
\end{array}
Initial program 99.1%
Taylor expanded in s around inf
*-commutativeN/A
lower-*.f32N/A
fp-cancel-sub-sign-invN/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f32N/A
distribute-rgt-out--N/A
metadata-evalN/A
lower-*.f32N/A
lower-PI.f32N/A
lower-*.f32N/A
lower-PI.f3211.4
Applied rewrites11.4%
Taylor expanded in u around 0
Applied rewrites11.4%
(FPCore (u s) :precision binary32 (- (PI)))
\begin{array}{l}
\\
-\mathsf{PI}\left(\right)
\end{array}
Initial program 99.1%
Taylor expanded in u around 0
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.2
Applied rewrites11.2%
herbie shell --seed 2025017
(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))))