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/*
* Implement sin(pi * x) and cos(pi * x) for real x. Since the periods
* of these functions are integral (and thus representable in double
* precision), it's possible to compute them with greater accuracy
* than sin(x) and cos(x).
*/
use crate::cephes64::M_PI;
/* Compute sin(pi * x). */
pub fn sinpi(x: f64) -> f64
{
let mut s: f64 = 1.0;
let mut x = x;
if x < 0.0 {
x = -x;
s = -1.0;
}
let r = x % 2.0;
if r < 0.5 {
s * (M_PI * r).sin()
} else if r > 1.5 {
s * (M_PI * (r - 2.0)).sin()
}
else {
-s * (M_PI * (r - 1.0)).sin()
}
}
/* Compute cos(pi * x) */
pub fn cospi(x: f64) -> f64
{
let r = x.abs() % 2.0;
if r == 0.5 {
// We don't want to return -0.0
0.0
} else if r < 1.0 {
-(M_PI * (r - 0.5)).sin()
}
else {
(M_PI * (r - 1.5)).sin()
}
}