
(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 9 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 (cbrt (PI))))
(*
(log
(-
(/
1.0
(+
(/ 1.0 (+ (exp (* (* (/ 1.0 s) t_0) (pow t_0 2.0))) 1.0))
(*
(-
(/ -1.0 (+ (exp (/ (PI) s)) 1.0))
(/ -1.0 (+ (exp (/ (- (PI)) s)) 1.0)))
u)))
1.0))
(- s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt[3]{\mathsf{PI}\left(\right)}\\
\log \left(\frac{1}{\frac{1}{e^{\left(\frac{1}{s} \cdot t\_0\right) \cdot {t\_0}^{2}} + 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) \cdot \left(-s\right)
\end{array}
\end{array}
Initial program 98.9%
lift-/.f32N/A
div-invN/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.f32N/A
lower-/.f3298.9
Applied rewrites98.9%
Final simplification98.9%
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ (PI) s)) (t_1 (/ -1.0 (+ (exp t_0) 1.0))))
(if (<=
(*
(log
(-
-1.0
(/
-1.0
(- (* (- t_1 (/ -1.0 (+ (exp (/ (- (PI)) s)) 1.0))) u) t_1))))
(- s))
-9.999999960041972e-12)
(* (log (* (- (/ (+ t_0 1.0) u) (* 2.0 t_0)) u)) (- s))
(*
(log
(fma
(fma (* (PI) u) -0.5 (* (pow (pow (PI) 3.0) 0.3333333333333333) 0.25))
(/ 4.0 s)
1.0))
(- s)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{\mathsf{PI}\left(\right)}{s}\\
t_1 := \frac{-1}{e^{t\_0} + 1}\\
\mathbf{if}\;\log \left(-1 - \frac{-1}{\left(t\_1 - \frac{-1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1}\right) \cdot u - t\_1}\right) \cdot \left(-s\right) \leq -9.999999960041972 \cdot 10^{-12}:\\
\;\;\;\;\log \left(\left(\frac{t\_0 + 1}{u} - 2 \cdot t\_0\right) \cdot u\right) \cdot \left(-s\right)\\
\mathbf{else}:\\
\;\;\;\;\log \left(\mathsf{fma}\left(\mathsf{fma}\left(\mathsf{PI}\left(\right) \cdot u, -0.5, {\left({\mathsf{PI}\left(\right)}^{3}\right)}^{0.3333333333333333} \cdot 0.25\right), \frac{4}{s}, 1\right)\right) \cdot \left(-s\right)\\
\end{array}
\end{array}
if (*.f32 (neg.f32 s) (log.f32 (-.f32 (/.f32 #s(literal 1 binary32) (+.f32 (*.f32 u (-.f32 (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (PI.f32)) s)))) (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (PI.f32) s)))))) (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (PI.f32) s)))))) #s(literal 1 binary32)))) < -9.99999996e-12Initial program 99.0%
Taylor expanded in s around -inf
associate-*r/N/A
+-commutativeN/A
*-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
Applied rewrites6.9%
Taylor expanded in u around -inf
Applied rewrites29.7%
if -9.99999996e-12 < (*.f32 (neg.f32 s) (log.f32 (-.f32 (/.f32 #s(literal 1 binary32) (+.f32 (*.f32 u (-.f32 (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (neg.f32 (PI.f32)) s)))) (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (PI.f32) s)))))) (/.f32 #s(literal 1 binary32) (+.f32 #s(literal 1 binary32) (exp.f32 (/.f32 (PI.f32) s)))))) #s(literal 1 binary32)))) Initial program 98.8%
Taylor expanded in s around -inf
associate-*r/N/A
+-commutativeN/A
*-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
Applied rewrites11.9%
Applied rewrites28.9%
Final simplification29.3%
(FPCore (u s)
:precision binary32
(let* ((t_0 (/ -1.0 (+ (exp (/ (PI) s)) 1.0))))
(*
(log
(-
-1.0
(/ -1.0 (- (* (- t_0 (/ -1.0 (+ (exp (/ (- (PI)) s)) 1.0))) u) t_0))))
(- s))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{-1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}\\
\log \left(-1 - \frac{-1}{\left(t\_0 - \frac{-1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1}\right) \cdot u - t\_0}\right) \cdot \left(-s\right)
\end{array}
\end{array}
Initial program 98.9%
Final simplification98.9%
(FPCore (u s)
:precision binary32
(*
(log
(/
(-
(/
-1.0
(-
(/ -1.0 (+ (exp (/ (- (PI)) s)) 1.0))
(/ -1.0 (+ (exp (/ (PI) s)) 1.0))))
u)
u))
(- s)))\begin{array}{l}
\\
\log \left(\frac{\frac{-1}{\frac{-1}{e^{\frac{-\mathsf{PI}\left(\right)}{s}} + 1} - \frac{-1}{e^{\frac{\mathsf{PI}\left(\right)}{s}} + 1}} - u}{u}\right) \cdot \left(-s\right)
\end{array}
Initial program 98.9%
Taylor expanded in u around inf
lower--.f32N/A
Applied rewrites98.5%
Taylor expanded in u around 0
Applied rewrites98.8%
Final simplification98.8%
(FPCore (u s)
:precision binary32
(*
(log
(/
(/ -1.0 u)
(-
(/ -1.0 (+ (exp (/ (- (PI)) s)) 1.0))
(/ -1.0 (+ (exp (/ (PI) s)) 1.0)))))
(- s)))\begin{array}{l}
\\
\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}}\right) \cdot \left(-s\right)
\end{array}
Initial program 98.9%
Taylor expanded in u around inf
lower--.f32N/A
Applied rewrites98.5%
Taylor expanded in u around 0
Applied rewrites98.8%
Taylor expanded in u around 0
Applied rewrites76.3%
Final simplification76.3%
(FPCore (u s) :precision binary32 (* (log (+ (/ (PI) s) 1.0)) (- s)))
\begin{array}{l}
\\
\log \left(\frac{\mathsf{PI}\left(\right)}{s} + 1\right) \cdot \left(-s\right)
\end{array}
Initial program 98.9%
Taylor expanded in s around -inf
associate-*r/N/A
+-commutativeN/A
*-commutativeN/A
associate-/l*N/A
lower-fma.f32N/A
Applied rewrites10.3%
Taylor expanded in u around 0
Applied rewrites25.1%
Final simplification25.1%
(FPCore (u s) :precision binary32 (* (/ (PI) s) (/ (* (- s) s) s)))
\begin{array}{l}
\\
\frac{\mathsf{PI}\left(\right)}{s} \cdot \frac{\left(-s\right) \cdot s}{s}
\end{array}
Initial program 98.9%
Taylor expanded in u around inf
lower--.f32N/A
Applied rewrites98.5%
Taylor expanded in u around 0
lower-/.f32N/A
lower-PI.f3211.0
Applied rewrites11.0%
lift-neg.f32N/A
neg-sub0N/A
flip--N/A
metadata-evalN/A
lift-*.f32N/A
neg-sub0N/A
lower-/.f32N/A
lift-*.f32N/A
distribute-lft-neg-inN/A
lift-neg.f32N/A
lower-*.f32N/A
lower-+.f3213.4
Applied rewrites13.4%
Final simplification13.4%
(FPCore (u s) :precision binary32 (- (* (* (PI) u) 2.0) (PI)))
\begin{array}{l}
\\
\left(\mathsf{PI}\left(\right) \cdot u\right) \cdot 2 - \mathsf{PI}\left(\right)
\end{array}
Initial program 98.9%
Taylor expanded in u around inf
lower--.f32N/A
Applied rewrites98.5%
Taylor expanded in u around 0
Applied rewrites98.8%
Taylor expanded in s around inf
cancel-sign-sub-invN/A
metadata-evalN/A
distribute-lft-inN/A
distribute-rgt-out--N/A
metadata-evalN/A
associate-*r*N/A
*-commutativeN/A
associate-*r*N/A
metadata-evalN/A
associate-*r*N/A
metadata-evalN/A
lower-fma.f32N/A
*-commutativeN/A
lower-*.f32N/A
lower-PI.f32N/A
mul-1-negN/A
lower-neg.f32N/A
lower-PI.f3211.0
Applied rewrites11.0%
Applied rewrites11.2%
(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.f3211.0
Applied rewrites11.0%
herbie shell --seed 2024331
(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))))