
(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
(let* ((t_0 (acos (/ (- g) h)))
(t_1 (cos (fma 0.3333333333333333 t_0 (* -0.6666666666666666 (PI))))))
(*
(/
(* 2.0 (cos (fma 0.3333333333333333 t_0 (* (PI) 0.6666666666666666))))
t_1)
t_1)))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos^{-1} \left(\frac{-g}{h}\right)\\
t_1 := \cos \left(\mathsf{fma}\left(0.3333333333333333, t\_0, -0.6666666666666666 \cdot \mathsf{PI}\left(\right)\right)\right)\\
\frac{2 \cdot \cos \left(\mathsf{fma}\left(0.3333333333333333, t\_0, \mathsf{PI}\left(\right) \cdot 0.6666666666666666\right)\right)}{t\_1} \cdot t\_1
\end{array}
\end{array}
Initial program 98.4%
Applied rewrites98.4%
Applied rewrites99.9%
Final simplification99.9%
(FPCore (g h)
:precision binary64
(*
(cos
(fma
(* -0.1111111111111111 (PI))
-6.0
(* (acos (/ (- g) h)) 0.3333333333333333)))
2.0))\begin{array}{l}
\\
\cos \left(\mathsf{fma}\left(-0.1111111111111111 \cdot \mathsf{PI}\left(\right), -6, \cos^{-1} \left(\frac{-g}{h}\right) \cdot 0.3333333333333333\right)\right) \cdot 2
\end{array}
Initial program 98.4%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-/.f64N/A
frac-2negN/A
frac-addN/A
clear-numN/A
lower-/.f64N/A
lower-/.f64N/A
metadata-evalN/A
metadata-evalN/A
distribute-rgt-neg-outN/A
*-commutativeN/A
distribute-lft-neg-outN/A
lower-fma.f64N/A
Applied rewrites98.5%
lift-/.f64N/A
lift-/.f64N/A
associate-/r/N/A
lift-fma.f64N/A
+-commutativeN/A
distribute-rgt-inN/A
lower-fma.f64N/A
lift-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
metadata-evalN/A
lower-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
metadata-eval98.5
Applied rewrites98.5%
lift-fma.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
metadata-evalN/A
lower-fma.f64N/A
lower-*.f64N/A
lower-*.f6498.5
Applied rewrites98.5%
Final simplification98.5%
(FPCore (g h) :precision binary64 (* (cos (fma (PI) 0.6666666666666666 (* (acos (/ (- g) h)) 0.3333333333333333))) 2.0))
\begin{array}{l}
\\
\cos \left(\mathsf{fma}\left(\mathsf{PI}\left(\right), 0.6666666666666666, \cos^{-1} \left(\frac{-g}{h}\right) \cdot 0.3333333333333333\right)\right) \cdot 2
\end{array}
Initial program 98.4%
lift-+.f64N/A
lift-/.f64N/A
div-invN/A
lift-*.f64N/A
*-commutativeN/A
associate-*l*N/A
lower-fma.f64N/A
metadata-evalN/A
metadata-eval98.5
lift-/.f64N/A
clear-numN/A
associate-/r/N/A
lower-*.f64N/A
metadata-eval98.5
Applied rewrites98.5%
Final simplification98.5%
herbie shell --seed 2024242
(FPCore (g h)
:name "2-ancestry mixing, negative discriminant"
:precision binary64
(* 2.0 (cos (+ (/ (* 2.0 (PI)) 3.0) (/ (acos (/ (- g) h)) 3.0)))))