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use super::ComplexVector;
use crate::{Complex64, to_i32};
unsafe extern "C" {
// Scales a vector by a constant
// <https://www.netlib.org/lapack/explore-html/d2/d74/zscal_8f.html>
fn cblas_zscal(n: i32, alpha: *const Complex64, x: *mut Complex64, incx: i32);
}
/// Scales a complex vector by a constant
///
/// ```text
/// u := alpha * u
/// ```
///
/// See also: <https://www.netlib.org/lapack/explore-html/d2/d74/zscal_8f.html>
///
/// # Examples
///
/// ```
/// use russell_lab::*;
///
/// fn main() {
/// let mut u = ComplexVector::from(&[cpx!(1.0, 1.0), cpx!(2.0, -2.0), cpx!(3.0, 3.0)]);
/// complex_vec_scale(&mut u, cpx!(0.5, -0.5));
/// println!("{}", u);
/// let correct = "┌ ┐\n\
/// │ 1+0i │\n\
/// │ 0-2i │\n\
/// │ 3+0i │\n\
/// └ ┘";
/// assert_eq!(format!("{}", u), correct);
/// }
/// ```
pub fn complex_vec_scale(v: &mut ComplexVector, alpha: Complex64) {
let n_i32: i32 = to_i32(v.dim());
unsafe {
cblas_zscal(n_i32, &alpha, v.as_mut_data().as_mut_ptr(), 1);
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#[cfg(test)]
mod tests {
use super::complex_vec_scale;
use crate::{ComplexVector, complex_vec_approx_eq, cpx};
#[test]
fn complex_vec_scale_works() {
let mut u = ComplexVector::from(&[6.0, 9.0, 12.0]);
complex_vec_scale(&mut u, cpx!(1.0 / 3.0, 0.0));
let correct = &[cpx!(2.0, 0.0), cpx!(3.0, 0.0), cpx!(4.0, 0.0)];
complex_vec_approx_eq(&u, correct, 1e-15);
}
}