61 lines
2.0 KiB
Rust
61 lines
2.0 KiB
Rust
use alga::general::Real;
|
|
|
|
use core::{DefaultAllocator, SquareMatrix};
|
|
use core::dimension::DimMin;
|
|
use core::storage::Storage;
|
|
use core::allocator::Allocator;
|
|
|
|
use linalg::LU;
|
|
|
|
impl<N: Real, D: DimMin<D, Output = D>, S: Storage<N, D, D>> SquareMatrix<N, D, S> {
|
|
/// Computes the matrix determinant.
|
|
///
|
|
/// If the matrix has a dimension larger than 3, an LU decomposition is used.
|
|
#[inline]
|
|
pub fn determinant(&self) -> N
|
|
where
|
|
DefaultAllocator: Allocator<N, D, D> + Allocator<(usize, usize), D>,
|
|
{
|
|
assert!(
|
|
self.is_square(),
|
|
"Unable to compute the determinant of a non-square matrix."
|
|
);
|
|
let dim = self.shape().0;
|
|
|
|
unsafe {
|
|
match dim {
|
|
0 => N::one(),
|
|
1 => *self.get_unchecked(0, 0),
|
|
2 => {
|
|
let m11 = *self.get_unchecked(0, 0);
|
|
let m12 = *self.get_unchecked(0, 1);
|
|
let m21 = *self.get_unchecked(1, 0);
|
|
let m22 = *self.get_unchecked(1, 1);
|
|
|
|
m11 * m22 - m21 * m12
|
|
}
|
|
3 => {
|
|
let m11 = *self.get_unchecked(0, 0);
|
|
let m12 = *self.get_unchecked(0, 1);
|
|
let m13 = *self.get_unchecked(0, 2);
|
|
|
|
let m21 = *self.get_unchecked(1, 0);
|
|
let m22 = *self.get_unchecked(1, 1);
|
|
let m23 = *self.get_unchecked(1, 2);
|
|
|
|
let m31 = *self.get_unchecked(2, 0);
|
|
let m32 = *self.get_unchecked(2, 1);
|
|
let m33 = *self.get_unchecked(2, 2);
|
|
|
|
let minor_m12_m23 = m22 * m33 - m32 * m23;
|
|
let minor_m11_m23 = m21 * m33 - m31 * m23;
|
|
let minor_m11_m22 = m21 * m32 - m31 * m22;
|
|
|
|
m11 * minor_m12_m23 - m12 * minor_m11_m23 + m13 * minor_m11_m22
|
|
}
|
|
_ => LU::new(self.clone_owned()).determinant(),
|
|
}
|
|
}
|
|
}
|
|
}
|