
(FPCore (v) :precision binary64 (/ 4.0 (* (* (* 3.0 (PI)) (- 1.0 (* v v))) (sqrt (- 2.0 (* 6.0 (* v v)))))))
\begin{array}{l}
\\
\frac{4}{\left(\left(3 \cdot \mathsf{PI}\left(\right)\right) \cdot \left(1 - v \cdot v\right)\right) \cdot \sqrt{2 - 6 \cdot \left(v \cdot v\right)}}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 4 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (v) :precision binary64 (/ 4.0 (* (* (* 3.0 (PI)) (- 1.0 (* v v))) (sqrt (- 2.0 (* 6.0 (* v v)))))))
\begin{array}{l}
\\
\frac{4}{\left(\left(3 \cdot \mathsf{PI}\left(\right)\right) \cdot \left(1 - v \cdot v\right)\right) \cdot \sqrt{2 - 6 \cdot \left(v \cdot v\right)}}
\end{array}
(FPCore (v) :precision binary64 (/ 4.0 (* (* (sqrt (fma -6.0 (* v v) 2.0)) 3.0) (* (- 1.0 (* v v)) (PI)))))
\begin{array}{l}
\\
\frac{4}{\left(\sqrt{\mathsf{fma}\left(-6, v \cdot v, 2\right)} \cdot 3\right) \cdot \left(\left(1 - v \cdot v\right) \cdot \mathsf{PI}\left(\right)\right)}
\end{array}
Initial program 98.5%
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
lower-fma.f64N/A
metadata-evalN/A
*-commutativeN/A
lower-*.f64100.0
Applied rewrites100.0%
(FPCore (v) :precision binary64 (* (/ 2.0 (* (sqrt (fma -6.0 (* v v) 2.0)) 3.0)) (/ 2.0 (PI))))
\begin{array}{l}
\\
\frac{2}{\sqrt{\mathsf{fma}\left(-6, v \cdot v, 2\right)} \cdot 3} \cdot \frac{2}{\mathsf{PI}\left(\right)}
\end{array}
Initial program 98.5%
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
lower-fma.f64N/A
metadata-evalN/A
*-commutativeN/A
lower-*.f64100.0
Applied rewrites100.0%
Taylor expanded in v around 0
lower-PI.f6499.6
Applied rewrites99.6%
lift-/.f64N/A
metadata-evalN/A
lift-*.f64N/A
times-fracN/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6499.6
Applied rewrites99.6%
(FPCore (v) :precision binary64 (/ 4.0 (* (* (sqrt (fma -6.0 (* v v) 2.0)) 3.0) (PI))))
\begin{array}{l}
\\
\frac{4}{\left(\sqrt{\mathsf{fma}\left(-6, v \cdot v, 2\right)} \cdot 3\right) \cdot \mathsf{PI}\left(\right)}
\end{array}
Initial program 98.5%
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*l*N/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
lower-fma.f64N/A
metadata-evalN/A
*-commutativeN/A
lower-*.f64100.0
Applied rewrites100.0%
Taylor expanded in v around 0
lower-PI.f6499.6
Applied rewrites99.6%
(FPCore (v) :precision binary64 (* (sqrt 0.5) (/ 1.3333333333333333 (PI))))
\begin{array}{l}
\\
\sqrt{0.5} \cdot \frac{1.3333333333333333}{\mathsf{PI}\left(\right)}
\end{array}
Initial program 98.5%
Taylor expanded in v around 0
*-commutativeN/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
lower-PI.f6498.1
Applied rewrites98.1%
Applied rewrites99.6%
herbie shell --seed 2025017
(FPCore (v)
:name "Falkner and Boettcher, Equation (22+)"
:precision binary64
(/ 4.0 (* (* (* 3.0 (PI)) (- 1.0 (* v v))) (sqrt (- 2.0 (* 6.0 (* v v)))))))