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//! Implementation of ?getrs - Solve a system of linear equations using LU factorization.
use lapack::{cgetrs, dgetrs, sgetrs, zgetrs};
use crate::base_types::LapackResult;
use crate::base_types::{c32, c64};
use crate::dense::linalg::lapack::interface::lapack_return;
/// Transpose modes for the `?getrs` function.
#[derive(Clone, Copy)]
#[repr(u8)]
pub enum GetrsTransMode {
/// No transpose, solve `AX = b`.
NoTranspose = b'N',
/// Transpose, solve `A^T X = b`.
Transpose = b'T',
/// Conjugate transpose, solve `A^H X = b`.
ConjugateTranspose = b'C',
}
/// ?getrs - Solve a system of linear equations using LU factorization.
///
/// **Arguments:**
///
///
///
/// **Returns:**
/// - The Lapack info code if the solve fails.
pub trait Getrs: Sized {
/// Solve a system of linear equations using LU factorization.
#[allow(clippy::too_many_arguments)]
fn getrs(
trans: GetrsTransMode,
n: usize,
nrhs: usize,
a: &[Self],
lda: usize,
ipiv: &[i32],
b: &mut [Self],
ldb: usize,
) -> LapackResult<()>;
}
macro_rules! implement_getrs {
($scalar:ty, $getrs:expr) => {
impl Getrs for $scalar {
fn getrs(
trans: GetrsTransMode,
n: usize,
nrhs: usize,
a: &[Self],
lda: usize,
ipiv: &[i32],
b: &mut [Self],
ldb: usize,
) -> LapackResult<()> {
let mut info = 0;
assert!(
lda >= std::cmp::max(1, n),
"Require `lda` {} >= `max(1, N)` {} .",
lda,
std::cmp::max(1, n)
);
assert_eq!(
a.len(),
lda * n,
"Require `a.len()` {} == `lda * n` {}.",
a.len(),
lda * n,
);
assert_eq!(
ipiv.len(),
n,
"Require `ipiv.len()` {} == `n` {}.",
ipiv.len(),
n,
);
assert!(
ldb >= std::cmp::max(1, n),
"Require `ldb` {} >= `max(1, N)` {} .",
ldb,
std::cmp::max(1, n)
);
assert_eq!(
b.len(),
ldb * nrhs,
"Require `b.len()` {} == `ldb * nrhs` {}.",
b.len(),
ldb * nrhs,
);
unsafe {
$getrs(
trans as u8,
n as i32,
nrhs as i32,
a,
lda as i32,
ipiv,
b,
ldb as i32,
&mut info,
);
}
lapack_return(info, ())
}
}
};
}
implement_getrs!(f32, sgetrs);
implement_getrs!(f64, dgetrs);
implement_getrs!(c32, cgetrs);
implement_getrs!(c64, zgetrs);