vectormatrix 0.1.2

Idiomatic Matrix and Vector types for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73

// SPDX-License-Identifier: MIT OR Apache-2.0
/*!
2x2 matrix algorithms
*/

use crate::matrix::Matrix;
use crate::types::sealed::Constants;
use crate::vector::Vector;

impl<T> Matrix<T, 2, 2> {
    #[inline]
    pub fn determinant(self) -> T
    where
        T: Clone + core::ops::Sub<Output = T> + core::ops::Mul<Output = T>,
    {
        let a = self.columns()[0].x().clone();
        let b = self.columns()[1].x().clone();
        let c = self.columns()[0].y().clone();
        let d = self.columns()[1].y().clone();
        a * d - b * c
    }

    /**
        Finds the inverse of the matrix.
    */
    pub fn inverse(self) -> Option<Self>
    where
        T: Constants
            + core::ops::Div<Output = T>
            + core::ops::Sub<Output = T>
            + core::ops::Mul<Output = T>
            + core::cmp::PartialEq
            + core::ops::Neg<Output = T>
            + Clone,
    {
        let det = self.clone().determinant();
        if det == T::ZERO {
            None
        } else {
            let det_inverse = T::ONE / det;
            let a = self.columns()[0].x().clone();
            let b = self.columns()[1].x().clone();
            let c = self.columns()[0].y().clone();
            let d = self.columns()[1].y().clone();
            let mat = Matrix::new_columns([Vector::new([d, -c]), Vector::new([-b, a])]);
            Some(mat * det_inverse)
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::matrix::Matrix;
    use crate::vector::Vector;

    #[test]
    fn determinant() {
        let m = Matrix::new_rows([Vector::new([3, 7]), Vector::new([1, -4])]);
        assert_eq!(m.determinant(), -19);
    }
    #[test]
    fn inverse() {
        let m = Matrix::new_rows([Vector::new([3.0f32, 7.0]), Vector::new([1.0, -4.0])]);
        let inv = m.inverse().unwrap();
        assert_eq!(
            inv,
            Matrix::new_rows([
                Vector::new([4.0 / 19.0, 7.0 / 19.0]),
                Vector::new([1.0 / 19.0, -3.0 / 19.0]),
            ])
        );
    }
}