
(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 8 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 (sqrt (fma -0.5 x 0.5)))
(t_1 (asin t_0))
(t_2 (pow t_1 2.0))
(t_3 (* (PI) (PI))))
(/
(*
(fma t_1 2.0 (* (PI) -0.5))
(fma
-16.0
(pow (- (* (PI) 0.5) (acos t_0)) 4.0)
(* 0.0625 (pow (PI) 4.0))))
(* (fma t_2 4.0 (* t_3 -0.25)) (fma t_2 4.0 (* t_3 0.25))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\\
t_1 := \sin^{-1} t\_0\\
t_2 := {t\_1}^{2}\\
t_3 := \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\\
\frac{\mathsf{fma}\left(t\_1, 2, \mathsf{PI}\left(\right) \cdot -0.5\right) \cdot \mathsf{fma}\left(-16, {\left(\mathsf{PI}\left(\right) \cdot 0.5 - \cos^{-1} t\_0\right)}^{4}, 0.0625 \cdot {\mathsf{PI}\left(\right)}^{4}\right)}{\mathsf{fma}\left(t\_2, 4, t\_3 \cdot -0.25\right) \cdot \mathsf{fma}\left(t\_2, 4, t\_3 \cdot 0.25\right)}
\end{array}
\end{array}
Initial program 6.1%
Applied rewrites6.1%
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%
Applied rewrites7.6%
Taylor expanded in x around 0
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (asin (sqrt (fma x -0.5 0.5))))
(t_1 (* (PI) (PI)))
(t_2 (* t_1 -0.25))
(t_3 (pow t_0 2.0)))
(/
(-
(* (* (* (PI) -0.25) t_2) (PI))
(pow (* (fma (PI) 0.5 (- (acos (sqrt (fma -0.5 x 0.5))))) 2.0) 4.0))
(/
(* (fma t_3 4.0 (* t_1 0.25)) (fma t_3 4.0 t_2))
(fma 2.0 t_0 (* (PI) -0.5))))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
t_1 := \mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\\
t_2 := t\_1 \cdot -0.25\\
t_3 := {t\_0}^{2}\\
\frac{\left(\left(\mathsf{PI}\left(\right) \cdot -0.25\right) \cdot t\_2\right) \cdot \mathsf{PI}\left(\right) - {\left(\mathsf{fma}\left(\mathsf{PI}\left(\right), 0.5, -\cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right)\right) \cdot 2\right)}^{4}}{\frac{\mathsf{fma}\left(t\_3, 4, t\_1 \cdot 0.25\right) \cdot \mathsf{fma}\left(t\_3, 4, t\_2\right)}{\mathsf{fma}\left(2, t\_0, \mathsf{PI}\left(\right) \cdot -0.5\right)}}
\end{array}
\end{array}
Initial program 6.1%
Applied rewrites6.1%
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%
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
associate-*r*N/A
lower-*.f64N/A
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (* (PI) 0.5)) (t_1 (sqrt (fma -0.5 x 0.5))) (t_2 (asin t_1)))
(/
(/
(fma -16.0 (pow (- t_0 (acos t_1)) 4.0) (* 0.0625 (pow (PI) 4.0)))
(fma t_2 2.0 t_0))
(fma (pow t_2 2.0) 4.0 (* (* (PI) (PI)) 0.25)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \mathsf{PI}\left(\right) \cdot 0.5\\
t_1 := \sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\\
t_2 := \sin^{-1} t\_1\\
\frac{\frac{\mathsf{fma}\left(-16, {\left(t\_0 - \cos^{-1} t\_1\right)}^{4}, 0.0625 \cdot {\mathsf{PI}\left(\right)}^{4}\right)}{\mathsf{fma}\left(t\_2, 2, t\_0\right)}}{\mathsf{fma}\left({t\_2}^{2}, 4, \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) \cdot 0.25\right)}
\end{array}
\end{array}
Initial program 6.1%
Applied rewrites6.1%
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
*-commutativeN/A
lift-*.f64N/A
associate-*l*N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
Applied rewrites7.6%
Taylor expanded in x around 0
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (asin (sqrt (fma x -0.5 0.5)))) (t_1 (* (* (PI) (PI)) 0.25)))
(/
(-
(* (* (PI) 0.25) (* t_1 (PI)))
(pow (fma (acos (sqrt (fma -0.5 x 0.5))) -2.0 (PI)) 4.0))
(* (fma t_0 2.0 (* (PI) 0.5)) (fma (pow t_0 2.0) 4.0 t_1)))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sin^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right)\\
t_1 := \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) \cdot 0.25\\
\frac{\left(\mathsf{PI}\left(\right) \cdot 0.25\right) \cdot \left(t\_1 \cdot \mathsf{PI}\left(\right)\right) - {\left(\mathsf{fma}\left(\cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right), -2, \mathsf{PI}\left(\right)\right)\right)}^{4}}{\mathsf{fma}\left(t\_0, 2, \mathsf{PI}\left(\right) \cdot 0.5\right) \cdot \mathsf{fma}\left({t\_0}^{2}, 4, t\_1\right)}
\end{array}
\end{array}
Initial program 6.1%
Applied rewrites6.1%
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
*-commutativeN/A
lift-*.f64N/A
associate-*l*N/A
*-commutativeN/A
lift-*.f64N/A
associate-*r*N/A
lower-*.f64N/A
Applied rewrites7.6%
Taylor expanded in x around 0
metadata-evalN/A
cancel-sign-sub-invN/A
sub-negN/A
+-commutativeN/A
distribute-lft-inN/A
*-commutativeN/A
distribute-lft-neg-outN/A
distribute-rgt-neg-inN/A
metadata-evalN/A
associate-*r*N/A
metadata-evalN/A
*-lft-identityN/A
lower-fma.f64N/A
Applied rewrites7.6%
Final simplification7.6%
(FPCore (x)
:precision binary64
(let* ((t_0 (acos (sqrt (fma -0.5 x 0.5)))))
(/
(fma
(* (- (* (* (PI) (PI)) 0.25) (pow t_0 2.0)) -2.0)
2.0
(fma (* (PI) 0.5) (PI) (* (acos (sqrt (fma x -0.5 0.5))) (PI))))
(* (fma 0.5 (PI) t_0) 2.0))))\begin{array}{l}
\\
\begin{array}{l}
t_0 := \cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right)\\
\frac{\mathsf{fma}\left(\left(\left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) \cdot 0.25 - {t\_0}^{2}\right) \cdot -2, 2, \mathsf{fma}\left(\mathsf{PI}\left(\right) \cdot 0.5, \mathsf{PI}\left(\right), \cos^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right) \cdot \mathsf{PI}\left(\right)\right)\right)}{\mathsf{fma}\left(0.5, \mathsf{PI}\left(\right), t\_0\right) \cdot 2}
\end{array}
\end{array}
Initial program 6.1%
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.f647.5
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 rewrites7.5%
Applied rewrites7.4%
lift-*.f64N/A
*-commutativeN/A
lift-fma.f64N/A
lift-*.f64N/A
lift-*.f64N/A
*-lft-identityN/A
distribute-rgt-inN/A
lower-fma.f64N/A
lower-*.f647.5
lift-fma.f64N/A
*-commutativeN/A
lift-fma.f647.5
Applied rewrites7.5%
Final simplification7.5%
(FPCore (x) :precision binary64 (/ (fma (pow (fma (PI) 0.5 (- (acos (sqrt (fma -0.5 x 0.5))))) 2.0) -4.0 (* (* (PI) (PI)) 0.25)) (fma (asin (sqrt (fma x -0.5 0.5))) 2.0 (* (PI) 0.5))))
\begin{array}{l}
\\
\frac{\mathsf{fma}\left({\left(\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)}^{2}, -4, \left(\mathsf{PI}\left(\right) \cdot \mathsf{PI}\left(\right)\right) \cdot 0.25\right)}{\mathsf{fma}\left(\sin^{-1} \left(\sqrt{\mathsf{fma}\left(x, -0.5, 0.5\right)}\right), 2, \mathsf{PI}\left(\right) \cdot 0.5\right)}
\end{array}
Initial program 6.1%
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.f647.5
lift-fma.f64N/A
*-commutativeN/A
lower-fma.f647.5
Applied rewrites7.5%
Final simplification7.5%
(FPCore (x) :precision binary64 (fma (acos (sqrt (fma -0.5 x 0.5))) 2.0 (* (PI) -0.5)))
\begin{array}{l}
\\
\mathsf{fma}\left(\cos^{-1} \left(\sqrt{\mathsf{fma}\left(-0.5, x, 0.5\right)}\right), 2, \mathsf{PI}\left(\right) \cdot -0.5\right)
\end{array}
Initial program 6.1%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
lower-fma.f64N/A
Applied rewrites6.1%
Taylor expanded in x around 0
Applied rewrites4.3%
lift-asin.f64N/A
asin-acosN/A
lift-PI.f64N/A
div-invN/A
metadata-evalN/A
*-commutativeN/A
lift-*.f64N/A
sub-negN/A
lift-*.f64N/A
*-commutativeN/A
lower-fma.f64N/A
lower-neg.f64N/A
lower-acos.f645.5
Applied rewrites5.5%
Taylor expanded in x around 0
metadata-evalN/A
cancel-sign-sub-invN/A
sub-negN/A
+-commutativeN/A
distribute-lft-inN/A
associate-+l+N/A
mul-1-negN/A
associate-*r*N/A
metadata-evalN/A
*-commutativeN/A
distribute-lft1-inN/A
metadata-evalN/A
neg-mul-1N/A
Applied rewrites7.5%
(FPCore (x) :precision binary64 (fma (asin (sqrt 0.5)) -2.0 (* (PI) 0.5)))
\begin{array}{l}
\\
\mathsf{fma}\left(\sin^{-1} \left(\sqrt{0.5}\right), -2, \mathsf{PI}\left(\right) \cdot 0.5\right)
\end{array}
Initial program 6.1%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
lower-fma.f64N/A
Applied rewrites6.1%
Taylor expanded in x around 0
Applied rewrites4.3%
Final simplification4.3%
(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 2024285
(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))))))