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use simba::scalar::ComplexField;
use crate::base::allocator::Allocator;
use crate::base::dimension::DimMin;
use crate::base::storage::Storage;
use crate::base::{DefaultAllocator, SquareMatrix};
use crate::linalg::LU;
impl<N: ComplexField, D: DimMin<D, Output = D>, S: Storage<N, D, D>> SquareMatrix<N, D, S> {
#[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(),
}
}
}
}