Matr_ijs 🔢

A small 2D f64 matrix library.

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

Note: The example below can be found in examples/basic.rs.

```rust // The matrix! macro allows for quick initialization.

// m = | 0.0 1.0 | // |-1.0 0.0 | let mut m = matrix![0.0, 1.0; -1.0, 0.0];

// Scalar math. m += 1.0; m *= -10.0;

// You can also create a Matrix manually. let mexpected = Matrix::new(2, 2, &[-10.0, -20.0, 0.0, -10.0]); asserteq!(m, m_expected);

// 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![0.0, 1.0; 2.0, 3.0]; let b = matrix![4.0, 5.0, 6.0; 7.0, 8.0, 9.0];

// The dot product of i and a should be equal to a (idempotence). let i = Matrix::identity(2); assert_eq!(i.dot(&a), a);

assert_eq!(a.dot(&b), matrix![7.0, 8.0, 9.0; 29.0, 34.0, 39.0]);

// You can append rows and columns to expand what you're working with. let mut ones = Matrix::one(2, 2); ones.append_row(matrix![0.0, 0.0].array());

assert_eq!( ones, matrix![ 1.0, 1.0; 1.0, 1.0; 0.0, 0.0 ] );

// When in doubt, take a look at the shape of the matrix. assert_eq!(ones.shape(), (3, 2)) // 3 rows, 2 columns ```

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>.