russell_lab 1.11.0

Scientific laboratory for linear algebra and numerical mathematics
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56

use super::ComplexVector;
use crate::{to_i32, Complex64};

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::{complex_vec_approx_eq, cpx, Complex64, ComplexVector};

    #[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);
    }
}