
(FPCore (g h) :precision binary64 (* 2.0 (cos (+ (/ (* 2.0 (PI)) 3.0) (/ (acos (/ (- g) h)) 3.0)))))
\begin{array}{l}
\\
2 \cdot \cos \left(\frac{2 \cdot \mathsf{PI}\left(\right)}{3} + \frac{\cos^{-1} \left(\frac{-g}{h}\right)}{3}\right)
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 3 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (g h) :precision binary64 (* 2.0 (cos (+ (/ (* 2.0 (PI)) 3.0) (/ (acos (/ (- g) h)) 3.0)))))
\begin{array}{l}
\\
2 \cdot \cos \left(\frac{2 \cdot \mathsf{PI}\left(\right)}{3} + \frac{\cos^{-1} \left(\frac{-g}{h}\right)}{3}\right)
\end{array}
(FPCore (g h) :precision binary64 (* (sin (fma (PI) -0.16666666666666666 (* (acos (/ (- g) h)) -0.3333333333333333))) 2.0))
\begin{array}{l}
\\
\sin \left(\mathsf{fma}\left(\mathsf{PI}\left(\right), -0.16666666666666666, \cos^{-1} \left(\frac{-g}{h}\right) \cdot -0.3333333333333333\right)\right) \cdot 2
\end{array}
Initial program 98.5%
lift-*.f64N/A
*-commutativeN/A
lower-*.f6498.5
Applied rewrites98.5%
Applied rewrites99.9%
Taylor expanded in g around 0
+-commutativeN/A
distribute-lft-inN/A
metadata-evalN/A
mul-1-negN/A
distribute-frac-negN/A
lower-acos.f64N/A
lift-/.f64N/A
lift-neg.f64N/A
lift-PI.f64N/A
*-commutativeN/A
associate-+r+N/A
Applied rewrites100.0%
(FPCore (g h) :precision binary64 (* (cos (fma (PI) 0.6666666666666666 (* 0.3333333333333333 (acos (/ (- g) h))))) 2.0))
\begin{array}{l}
\\
\cos \left(\mathsf{fma}\left(\mathsf{PI}\left(\right), 0.6666666666666666, 0.3333333333333333 \cdot \cos^{-1} \left(\frac{-g}{h}\right)\right)\right) \cdot 2
\end{array}
Initial program 98.5%
lift-*.f64N/A
*-commutativeN/A
lower-*.f6498.5
Applied rewrites98.5%
lift-/.f64N/A
lift-PI.f64N/A
lift-fma.f64N/A
*-commutativeN/A
div-add-revN/A
frac-addN/A
*-commutativeN/A
metadata-evalN/A
div-addN/A
*-commutativeN/A
associate-*r*N/A
metadata-evalN/A
associate-/l*N/A
metadata-evalN/A
associate-/l*N/A
Applied rewrites98.5%
(FPCore (g h) :precision binary64 (* 2.0 (cos (fma 0.3333333333333333 (acos (/ (- g) h)) (* 0.6666666666666666 (PI))))))
\begin{array}{l}
\\
2 \cdot \cos \left(\mathsf{fma}\left(0.3333333333333333, \cos^{-1} \left(\frac{-g}{h}\right), 0.6666666666666666 \cdot \mathsf{PI}\left(\right)\right)\right)
\end{array}
Initial program 98.5%
Taylor expanded in g around 0
mul-1-negN/A
distribute-frac-negN/A
lower-fma.f64N/A
lift-/.f64N/A
lift-neg.f64N/A
lift-acos.f64N/A
lower-*.f64N/A
lift-PI.f6498.5
Applied rewrites98.5%
herbie shell --seed 2025032
(FPCore (g h)
:name "2-ancestry mixing, negative discriminant"
:precision binary64
(* 2.0 (cos (+ (/ (* 2.0 (PI)) 3.0) (/ (acos (/ (- g) h)) 3.0)))))