
(FPCore (x) :precision binary64 (- (/ (PI) 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))
\begin{array}{l}
\\
\frac{\mathsf{PI}\left(\right)}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\right)
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x) :precision binary64 (- (/ (PI) 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))
\begin{array}{l}
\\
\frac{\mathsf{PI}\left(\right)}{2} - 2 \cdot \sin^{-1} \left(\sqrt{\frac{1 - x}{2}}\right)
\end{array}
(FPCore (x)
:precision binary64
(let* ((t_0 (asin (sqrt (fma x -0.5 0.5)))))
(/
(-
(* (* (* 0.25 (PI)) (* 0.25 (* (PI) (PI)))) (PI))
(pow (* 2.0 (fma (PI) 0.5 (- (acos (sqrt (fma -0.5 x 0.5)))))) 4.0))
(*
(fma (pow t_0 2.0) 4.0 (* (* (cbrt (pow (PI) 3.0)) (PI)) 0.25))
(fma t_0 2.0 (* 0.5 (PI)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
\frac{\left(\left(0.25 \cdot \mathsf{PI}\left(\right)\right) \cdot \left(0.25 \cdot \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right)\right)\right) \cdot \mathsf{PI}\left(\right) - {\left(2 \cdot \mathsf{fma}\left(\mathsf{PI}\left(\right), 0.5, -\cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right)\right)\right)}^{4}}{\mathsf{fma}\left({t\_0}^{2}, 4, \left(\sqrt[3]{{\mathsf{PI}\left(\right)}^{3}} \cdot \mathsf{PI}\left(\right)\right) \cdot 0.25\right) \cdot \mathsf{fma}\left(t\_0, 2, 0.5 \cdot \mathsf{PI}\left(\right)\right)}
\end{array}
\end{array}
Initial program 6.2%
Applied rewrites6.2%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
lift-/.f64N/A
lift-acos.f64N/A
unsub-negN/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
lift-neg.f64N/A
lift-fma.f647.6
lift-fma.f64N/A
*-commutativeN/A
lower-fma.f647.6
Applied rewrites7.6%
lift-pow.f64N/A
lift-*.f64N/A
unpow-prod-downN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
lift-*.f64N/A
pow2N/A
swap-sqrN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
Applied rewrites7.6%
rem-cbrt-cubeN/A
lower-cbrt.f64N/A
lower-pow.f647.6
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (* 0.25 (* (PI) (PI))))
(t_1 (sqrt (fma x -0.5 0.5)))
(t_2 (asin t_1)))
(/
(- (* (* (* 0.25 (PI)) t_0) (PI)) (pow (fma -2.0 (acos t_1) (PI)) 4.0))
(* (fma (pow t_2 2.0) 4.0 t_0) (fma t_2 2.0 (* 0.5 (PI)))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := 0.25 \cdot \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right)\\
t_1 := \sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\\
t_2 := \sin^{-1} t\_1\\
\frac{\left(\left(0.25 \cdot \mathsf{PI}\left(\right)\right) \cdot t\_0\right) \cdot \mathsf{PI}\left(\right) - {\left(\mathsf{fma}\left(-2, \cos^{-1} t\_1, \mathsf{PI}\left(\right)\right)\right)}^{4}}{\mathsf{fma}\left({t\_2}^{2}, 4, t\_0\right) \cdot \mathsf{fma}\left(t\_2, 2, 0.5 \cdot \mathsf{PI}\left(\right)\right)}
\end{array}
\end{array}
Initial program 6.2%
Applied rewrites6.2%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
lift-/.f64N/A
lift-acos.f64N/A
unsub-negN/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
lift-neg.f64N/A
lift-fma.f647.6
lift-fma.f64N/A
*-commutativeN/A
lower-fma.f647.6
Applied rewrites7.6%
lift-pow.f64N/A
lift-*.f64N/A
unpow-prod-downN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
pow-prod-upN/A
pow-prod-downN/A
lift-*.f64N/A
pow2N/A
swap-sqrN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
Applied rewrites7.6%
lift-*.f64N/A
*-commutativeN/A
lift-fma.f64N/A
metadata-evalN/A
div-invN/A
lift-PI.f64N/A
+-commutativeN/A
lift-fma.f64N/A
*-commutativeN/A
lift-fma.f64N/A
distribute-lft-inN/A
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (acos (sqrt (fma x -0.5 0.5)))))
(/
(- (* (* 0.25 (PI)) (PI)) (* (pow t_0 2.0) 4.0))
(fma -0.5 (PI) (* t_0 -2.0)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
\frac{\left(0.25 \cdot \mathsf{PI}\left(\right)\right) \cdot \mathsf{PI}\left(\right) - {t\_0}^{2} \cdot 4}{\mathsf{fma}\left(-0.5, \mathsf{PI}\left(\right), t\_0 \cdot -2\right)}
\end{array}
\end{array}
Initial program 6.2%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
lift-/.f64N/A
sub-negN/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
lower-fma.f64N/A
lower-neg.f64N/A
lower-acos.f647.6
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
sub-negN/A
+-commutativeN/A
div-invN/A
metadata-evalN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-fma.f64N/A
Applied rewrites7.6%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
sub-negN/A
metadata-evalN/A
cancel-sign-sub-invN/A
distribute-lft-inN/A
associate-+r+N/A
Applied rewrites7.6%
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x) :precision binary64 (fma -0.5 (PI) (* 2.0 (acos (sqrt (fma -0.5 x 0.5))))))
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \mathsf{PI}\left(\right), 2 \cdot \cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right)\right)
\end{array}
Initial program 6.2%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
lift-/.f64N/A
sub-negN/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
lower-fma.f64N/A
lower-neg.f64N/A
lower-acos.f647.6
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
sub-negN/A
+-commutativeN/A
div-invN/A
metadata-evalN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-fma.f64N/A
Applied rewrites7.6%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
sub-negN/A
metadata-evalN/A
cancel-sign-sub-invN/A
distribute-lft-inN/A
associate-+r+N/A
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x) :precision binary64 (fma -0.5 (PI) (* (acos (sqrt 0.5)) 2.0)))
\begin{array}{l}
\\
\mathsf{fma}\left(-0.5, \mathsf{PI}\left(\right), \cos^{-1} \left(\sqrt{0.5}\right) \cdot 2\right)
\end{array}
Initial program 6.2%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
lift-/.f64N/A
sub-negN/A
lift-/.f64N/A
div-invN/A
metadata-evalN/A
lower-fma.f64N/A
lower-neg.f64N/A
lower-acos.f647.6
lift-/.f64N/A
lift--.f64N/A
div-subN/A
metadata-evalN/A
sub-negN/A
+-commutativeN/A
div-invN/A
metadata-evalN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
metadata-evalN/A
metadata-evalN/A
lower-fma.f64N/A
Applied rewrites7.6%
Taylor expanded in x around 0
cancel-sign-sub-invN/A
metadata-evalN/A
sub-negN/A
metadata-evalN/A
cancel-sign-sub-invN/A
distribute-lft-inN/A
associate-+r+N/A
Applied rewrites7.6%
Taylor expanded in x around 0
Applied rewrites5.3%
(FPCore (x) :precision binary64 (asin x))
double code(double x) {
return asin(x);
}
real(8) function code(x)
real(8), intent (in) :: x
code = asin(x)
end function
public static double code(double x) {
return Math.asin(x);
}
def code(x): return math.asin(x)
function code(x) return asin(x) end
function tmp = code(x) tmp = asin(x); end
code[x_] := N[ArcSin[x], $MachinePrecision]
\begin{array}{l}
\\
\sin^{-1} x
\end{array}
herbie shell --seed 2024327
(FPCore (x)
:name "Ian Simplification"
:precision binary64
:alt
(! :herbie-platform default (asin x))
(- (/ (PI) 2.0) (* 2.0 (asin (sqrt (/ (- 1.0 x) 2.0))))))