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use super::Matrix;
use crate::{to_i32, StrError};
extern "C" {
// Copies a vector into another
// <https://www.netlib.org/lapack/explore-html/da/d6c/dcopy_8f.html>
fn cblas_dcopy(n: i32, x: *const f64, incx: i32, y: *mut f64, incy: i32);
}
/// (dcopy) Copies matrix
///
/// ```text
/// b := a
/// ```
///
/// See also: <https://www.netlib.org/lapack/explore-html/da/d6c/dcopy_8f.html>
///
/// # Examples
///
/// ```
/// use russell_lab::{mat_copy, Matrix, StrError};
///
/// fn main() -> Result<(), StrError> {
/// let a = Matrix::from(&[
/// [1.0, 2.0, 3.0],
/// [4.0, 5.0, 6.0],
/// ]);
/// let mut b = Matrix::from(&[
/// [-1.0, -2.0, -3.0],
/// [-4.0, -5.0, -6.0],
/// ]);
/// mat_copy(&mut b, &a)?;
/// let correct = "┌ ┐\n\
/// │ 1 2 3 │\n\
/// │ 4 5 6 │\n\
/// └ ┘";
/// assert_eq!(format!("{}", b), correct);
/// Ok(())
/// }
/// ```
pub fn mat_copy(b: &mut Matrix, a: &Matrix) -> Result<(), StrError> {
let (m, n) = b.dims();
if a.nrow() != m || a.ncol() != n {
return Err("matrices are incompatible");
}
let n_i32: i32 = to_i32(m * n);
unsafe {
cblas_dcopy(n_i32, a.as_data().as_ptr(), 1, b.as_mut_data().as_mut_ptr(), 1);
}
Ok(())
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#[cfg(test)]
mod tests {
use super::{mat_copy, Matrix};
use crate::mat_approx_eq;
#[test]
fn mat_copy_fails_on_wrong_dimensions() {
let a_2x2 = Matrix::new(2, 2);
let a_2x1 = Matrix::new(2, 1);
let a_1x2 = Matrix::new(1, 2);
let mut b_2x2 = Matrix::new(2, 2);
let mut b_2x1 = Matrix::new(2, 1);
let mut b_1x2 = Matrix::new(1, 2);
assert_eq!(mat_copy(&mut b_2x2, &a_2x1), Err("matrices are incompatible"));
assert_eq!(mat_copy(&mut b_2x2, &a_1x2), Err("matrices are incompatible"));
assert_eq!(mat_copy(&mut b_2x1, &a_2x2), Err("matrices are incompatible"));
assert_eq!(mat_copy(&mut b_1x2, &a_2x2), Err("matrices are incompatible"));
}
#[test]
fn mat_copy_works() {
#[rustfmt::skip]
let a = Matrix::from(&[
[10.0, 20.0, 30.0],
[40.0, 50.0, 60.0],
]);
#[rustfmt::skip]
let mut b = Matrix::from(&[
[100.0, 200.0, 300.0],
[400.0, 500.0, 600.0],
]);
mat_copy(&mut b, &a).unwrap();
#[rustfmt::skip]
let correct = &[
[10.0, 20.0, 30.0],
[40.0, 50.0, 60.0],
];
mat_approx_eq(&b, correct, 1e-15);
}
}