Matr_ijs 🔢

A small 2D f64 matrix library.

There are many like it, but this one is mine.

```rust use matrijs::Matrix;

// m = | 0.0 1.0 | // |-1.0 0.0 | let mut m = Matrix::new(2, 2, &[0.0, 1.0, -1.0, 0.0]); m += 1.0; assert_eq!(m, Matrix::new(2, 2, &[1.0, 2.0, 0.0, 1.0]));

// a = | 0.0 1.0 | // | 2.0 3.0 | // b = | 4.0 5.0 6.0 | // | 7.0 8.0 9.0 | let a = Matrix::new(2, 2, &[0.0, 1.0, 2.0, 3.0]); let b = Matrix::new(2, 3, &[4.0, 5.0, 6.0, 7.0, 8.0, 9.0]);

// Multiplication of i and a should be idempotent. let i = Matrix::identity(2); assert_eq!(i.dot(&a), a);

assert_eq!(a.dot(&b), Matrix::new(2, 3, &[7.0, 8.0, 9.0, 29.0, 34.0, 39.0])); ```

Abilities

• Creation
  • From array: Matrix::new(3, 2, &[0.0, 1.0, 2.0, 3.0, 4.0, 5.0])
  • With value: Matrix::with_value(3, 16.1)
  • Zeros: Matrix::zero(3)
  • Ones: Matrix::one(3)
  • Identity: Matrix::identity(3)
  • Diagonal: Matrix::diagonal(&[1.0, 3.0, 1.0, 2.0])
• Operations
  • Transpose
    • In place: m.transpose();
    • By value: m.t()
  • Scalar operations
    • Addition, subtraction, multiplication, division: b = a + 1.0, b *= 2
  • Matrix-matrix operations
    • Entry-by-entry addition, subtraction, multiplication, division: a + b
    • Dot product: a.dot(&b)

Implementation

The internal data structure is a Vec of entries, row after row. That means that this is a row-major implementation.

Name

In Dutch, there is a word matrijs (pronounce mat-rice) which has a common ancestor with the word matrix. Matrijs refers to molds or stamps, often when laid out in arrays.

I like the name for this library, because it contains the 'ij' digraph, which is very similar to the letters i and j as seen in notation for entries in a matrix, such as a<sub>ij</sub>.