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//! Implementation of ?sytrf/?hetrf - Factorization of a symmetric/Hermitian matrix.
use lapack::{chetrf, dsytrf, ssytrf, zhetrf};
use num::Zero;
use crate::base_types::{c32, c64};
use crate::dense::linalg::lapack::interface::lapack_return;
use crate::{base_types::LapackResult, traits::rlst_num::RlstScalar};
/// `Uplo` parameter for `?sytrf` to specify which triangular part of the matrix is stored.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum SytrfUplo {
/// Upper triangular part of the matrix is stored.
Upper = b'U',
/// Lower triangular part of the matrix is stored.
Lower = b'L',
}
/// ?sytrf/?hetrf - Factorization of a symmetric/Hermitian matrix.
pub trait Sytrf: RlstScalar {
/// Factor a symmetric/Hermitian `n x n` matrix in place with pivoting.
///
/// `a` is column-major; only `uplo` is read and its selected triangle is
/// overwritten with packed block-diagonal and triangular factors. `ipiv`
/// receives LAPACK's one-based pivot encoding. Invalid storage dimensions
/// panic; singular pivots and other LAPACK failures are returned as errors.
fn sytrf(
uplo: SytrfUplo,
n: usize,
a: &mut [Self],
lda: usize,
ipiv: &mut [i32],
) -> LapackResult<()>;
}
macro_rules! implement_sytrf {
($scalar:ty, $sytrf:expr) => {
impl Sytrf for $scalar {
fn sytrf(
uplo: SytrfUplo,
n: usize,
a: &mut [Self],
lda: usize,
ipiv: &mut [i32],
) -> LapackResult<()> {
let mut info = 0;
assert_eq!(
a.len(),
lda * n,
"Require `a.len()` {} == `lda * n` {}.",
a.len(),
lda * n
);
assert!(
lda >= std::cmp::max(1, n),
"Require `lda` {} >= `max(1, n)` {}.",
lda,
std::cmp::max(1, n)
);
assert_eq!(
ipiv.len(),
n,
"Require `ipiv.len()` {} == `n` {}.",
ipiv.len(),
n
);
let mut work = vec![<$scalar>::zero(); 1];
unsafe {
$sytrf(
uplo as u8, n as i32, a, lda as i32, ipiv, &mut work, -1, &mut info,
);
}
if info != 0 {
return Err(crate::base_types::LapackError::LapackInfoCode(info));
}
let lwork = work[0].re() as usize;
let mut work = vec![<$scalar>::zero(); lwork];
unsafe {
$sytrf(
uplo as u8,
n as i32,
a,
lda as i32,
ipiv,
&mut work,
lwork as i32,
&mut info,
);
}
lapack_return(info, ())
}
}
};
}
implement_sytrf!(f32, ssytrf);
implement_sytrf!(f64, dsytrf);
implement_sytrf!(c32, chetrf);
implement_sytrf!(c64, zhetrf);