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
74
75
76
77
78
79
80
81
82
83
84
85
86

use super::SparseMatrix;
use crate::{matrix::ge::Matrix, number::Number};
use std::ops::Mul;

fn mul<T>(slf: &SparseMatrix<T>, rhs: &Matrix<T>) -> Matrix<T>
where
    T: Number,
{
    if slf.cols != rhs.rows() {
        panic!("Dimension mismatch.");
    }
    let mut new_matrix = Matrix::new(slf.rows, rhs.cols());

    for (&(i, j), &s) in slf.elems.iter() {
        for k in 0..rhs.cols() {
            new_matrix[(k, i)] += s * rhs[(j, k)];
        }
    }

    new_matrix
}

impl<T> Mul<Matrix<T>> for SparseMatrix<T>
where
    T: Number,
{
    type Output = Matrix<T>;

    fn mul(self, rhs: Matrix<T>) -> Self::Output {
        mul(&self, &rhs)
    }
}

impl<T> Mul<&Matrix<T>> for SparseMatrix<T>
where
    T: Number,
{
    type Output = Matrix<T>;

    fn mul(self, rhs: &Matrix<T>) -> Self::Output {
        mul(&self, rhs)
    }
}

impl<T> Mul<Matrix<T>> for &SparseMatrix<T>
where
    T: Number,
{
    type Output = Matrix<T>;

    fn mul(self, rhs: Matrix<T>) -> Self::Output {
        mul(self, &rhs)
    }
}

impl<T> Mul<&Matrix<T>> for &SparseMatrix<T>
where
    T: Number,
{
    type Output = Matrix<T>;

    fn mul(self, rhs: &Matrix<T>) -> Self::Output {
        mul(self, rhs)
    }
}

#[cfg(test)]
mod tests {
    use crate::*;
    #[test]
    fn it_works() {
        let mut a = SparseMatrix::new(2, 3);
        a[(0, 0)] = 1.0;
        a[(0, 1)] = 2.0;
        a[(1, 2)] = 3.0;
        let b = mat![
            1.0, 3.0;
            2.0, 4.0;
            3.0, 6.0
        ];
        let c = a * b;

        assert_eq!(c[(0, 0)], 5.0);
        assert_eq!(c[(1, 1)], 18.0);
    }
}