
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (- (* alpha alpha) 1.0)))
(/
t_0
(* (* (PI) (log (* alpha alpha))) (+ 1.0 (* (* t_0 cosTheta) cosTheta))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \alpha \cdot \alpha - 1\\
\frac{t\_0}{\left(\mathsf{PI}\left(\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 + \left(t\_0 \cdot cosTheta\right) \cdot cosTheta\right)}
\end{array}
\end{array}
Sampling outcomes in binary32 precision:
Herbie found 11 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (- (* alpha alpha) 1.0)))
(/
t_0
(* (* (PI) (log (* alpha alpha))) (+ 1.0 (* (* t_0 cosTheta) cosTheta))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \alpha \cdot \alpha - 1\\
\frac{t\_0}{\left(\mathsf{PI}\left(\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 + \left(t\_0 \cdot cosTheta\right) \cdot cosTheta\right)}
\end{array}
\end{array}
(FPCore (cosTheta alpha)
:precision binary32
(let* ((t_0 (* (* cosTheta (fma alpha alpha -1.0)) cosTheta)))
(/
(- (* alpha alpha) 1.0)
(* (* (PI) (log (* alpha alpha))) (/ (- (pow t_0 2.0) 1.0) (- t_0 1.0))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(cosTheta \cdot \mathsf{fma}\left(\alpha, \alpha, -1\right)\right) \cdot cosTheta\\
\frac{\alpha \cdot \alpha - 1}{\left(\mathsf{PI}\left(\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \frac{{t\_0}^{2} - 1}{t\_0 - 1}}
\end{array}
\end{array}
Initial program 98.6%
lift-+.f32N/A
+-commutativeN/A
flip-+N/A
lower-/.f32N/A
Applied rewrites98.6%
(FPCore (cosTheta alpha) :precision binary32 (/ (- (* alpha alpha) 1.0) (* (* (PI) (log (* alpha alpha))) (fma (fma alpha alpha -1.0) (* cosTheta cosTheta) 1.0))))
\begin{array}{l}
\\
\frac{\alpha \cdot \alpha - 1}{\left(\mathsf{PI}\left(\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \mathsf{fma}\left(\mathsf{fma}\left(\alpha, \alpha, -1\right), cosTheta \cdot cosTheta, 1\right)}
\end{array}
Initial program 98.6%
lift-+.f32N/A
+-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-fma.f32N/A
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1-revN/A
lower-fma.f32N/A
lower-*.f3298.6
Applied rewrites98.6%
(FPCore (cosTheta alpha)
:precision binary32
(/
(fma alpha alpha -1.0)
(*
(*
(fma (* cosTheta cosTheta) (fma alpha alpha -1.0) 1.0)
(log (* alpha alpha)))
(PI))))\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\alpha, \alpha, -1\right)}{\left(\mathsf{fma}\left(cosTheta \cdot cosTheta, \mathsf{fma}\left(\alpha, \alpha, -1\right), 1\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.6%
lift-+.f32N/A
+-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-fma.f32N/A
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1-revN/A
lower-fma.f32N/A
lower-*.f3298.6
Applied rewrites98.6%
Applied rewrites98.5%
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1N/A
lift-fma.f3298.4
Applied rewrites98.4%
(FPCore (cosTheta alpha) :precision binary32 (/ (- (* alpha alpha) 1.0) (* (* (PI) (log (* alpha alpha))) (- 1.0 (* cosTheta cosTheta)))))
\begin{array}{l}
\\
\frac{\alpha \cdot \alpha - 1}{\left(\mathsf{PI}\left(\right) \cdot \log \left(\alpha \cdot \alpha\right)\right) \cdot \left(1 - cosTheta \cdot cosTheta\right)}
\end{array}
Initial program 98.6%
Taylor expanded in alpha around 0
Applied rewrites97.8%
(FPCore (cosTheta alpha) :precision binary32 (/ (fma alpha alpha -1.0) (* (* 2.0 (* (log alpha) (PI))) (- 1.0 (* cosTheta cosTheta)))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(\alpha, \alpha, -1\right)}{\left(2 \cdot \left(\log \alpha \cdot \mathsf{PI}\left(\right)\right)\right) \cdot \left(1 - cosTheta \cdot cosTheta\right)}
\end{array}
Initial program 98.6%
lift-+.f32N/A
+-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-fma.f32N/A
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1-revN/A
lower-fma.f32N/A
lower-*.f3298.6
Applied rewrites98.6%
Applied rewrites98.5%
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1N/A
lift-fma.f3298.4
Applied rewrites98.4%
Taylor expanded in alpha around 0
Applied rewrites97.8%
(FPCore (cosTheta alpha) :precision binary32 (/ (/ (fma alpha alpha -1.0) (PI)) (* 2.0 (log alpha))))
\begin{array}{l}
\\
\frac{\frac{\mathsf{fma}\left(\alpha, \alpha, -1\right)}{\mathsf{PI}\left(\right)}}{2 \cdot \log \alpha}
\end{array}
Initial program 98.6%
Taylor expanded in cosTheta around 0
Applied rewrites96.2%
Applied rewrites96.3%
(FPCore (cosTheta alpha) :precision binary32 (/ (- (* alpha alpha) 1.0) (* (log (* alpha alpha)) (PI))))
\begin{array}{l}
\\
\frac{\alpha \cdot \alpha - 1}{\log \left(\alpha \cdot \alpha\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.6%
lift-+.f32N/A
+-commutativeN/A
lift-*.f32N/A
lift-*.f32N/A
associate-*l*N/A
lower-fma.f32N/A
lift--.f32N/A
lift-*.f32N/A
difference-of-sqr-1N/A
difference-of-sqr--1-revN/A
lower-fma.f32N/A
lower-*.f3298.6
Applied rewrites98.6%
Taylor expanded in cosTheta around 0
Applied rewrites96.2%
Final simplification96.2%
(FPCore (cosTheta alpha) :precision binary32 (/ (fma (* 0.5 alpha) alpha -0.5) (* (log alpha) (PI))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(0.5 \cdot \alpha, \alpha, -0.5\right)}{\log \alpha \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.6%
Taylor expanded in cosTheta around 0
Applied rewrites96.2%
Taylor expanded in alpha around 0
Applied rewrites64.6%
Taylor expanded in alpha around 0
Applied rewrites96.2%
(FPCore (cosTheta alpha) :precision binary32 (/ (fma (* -0.5 cosTheta) cosTheta -0.5) (* (log alpha) (PI))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(-0.5 \cdot cosTheta, cosTheta, -0.5\right)}{\log \alpha \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.6%
Taylor expanded in alpha around 0
Applied rewrites65.5%
Taylor expanded in cosTheta around 0
Applied rewrites65.3%
(FPCore (cosTheta alpha) :precision binary32 (/ (/ -0.5 (PI)) (log alpha)))
\begin{array}{l}
\\
\frac{\frac{-0.5}{\mathsf{PI}\left(\right)}}{\log \alpha}
\end{array}
Initial program 98.6%
Taylor expanded in cosTheta around 0
Applied rewrites96.2%
Taylor expanded in alpha around 0
Applied rewrites64.6%
Applied rewrites64.7%
(FPCore (cosTheta alpha) :precision binary32 (/ -0.5 (* (log alpha) (PI))))
\begin{array}{l}
\\
\frac{-0.5}{\log \alpha \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.6%
Taylor expanded in cosTheta around 0
Applied rewrites96.2%
Taylor expanded in alpha around 0
Applied rewrites64.6%
herbie shell --seed 2025019
(FPCore (cosTheta alpha)
:name "GTR1 distribution"
:precision binary32
:pre (and (and (<= 0.0 cosTheta) (<= cosTheta 1.0)) (and (<= 0.0001 alpha) (<= alpha 1.0)))
(/ (- (* alpha alpha) 1.0) (* (* (PI) (log (* alpha alpha))) (+ 1.0 (* (* (- (* alpha alpha) 1.0) cosTheta) cosTheta)))))