js-mat

JavaScript library for representation and mathematical operations using matrix

Usage

Import the package as:

const {Matrix} = require('js-mat');

Create a matrix of random values:

var M = Matrix.rand(3,3); // create a 3x3 matrix

Create a null matrix:

var M = Matrix.zeros(2,5); // create a 2x5 null matrix

Create a matrix of ones:

var M = Matrix.ones(2,2) // create a 2x2 matrix of ones

Create an identity matrix:

var I = Matrix.eye(4); // identity matrix of size 4x4

Create a matrix from a 2D array:

var M = new Matrix([
    [1,2,3],
    [4,5,6],
    [7,8,9]
]);

Create a matrix from another matrix

var M1 = Matrix.rand(3,6);
var M2 = new Matrix(M1); // equal to M1

Operations

Addition:

var M1 = new Matrix([
    [12,7,9],
    [5,-2,3]
]);
var M2 = new Matrix([
    [-3.6, 0, 5.4],
    [-12,-2,7]
]);

var result = M1.add(M2);
// [8.4, 7, 14.4]
// [-7, -4, -10]

Substraction:

var M1 = new Matrix([
    [12,7,9],
    [5,-2,3]
]);
var M2 = new Matrix([
    [-3.6, 0, 5.4],
    [-12,-2,7]
]);

var result = M1.subs(M2);
// [15.6, 7.0, 3.6]
// [17.0, 0, -4.0]

Multiplication:

// Multiply two matrices
var M1 = new Matrix([
    [1, 2, 9],
    [-3, 7, 1]
]);

var M2 = new Matrix([
    [-5, 1],
    [3, 12],
    [1, 1]
]);

var result = M1.multiply(M2);
// [10, 34]
// [37, 82]

// Multiply a matrix by a constant
var M1 = new Matrix([
    [1, 2, 9],
    [-3, 7, 1]
]);

var result = M1.multiply(5);
// [5, 10, 45]
// [-15, 35, 5]

Determinant:

var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0],
    [3, -1, -9, 4]
]);

M.det(); // returns 88

Inverse:

var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0],
    [3, -1, -9, 4]
]);

M.inv();

// [-0.1364,    0.8636,   -0.6818,   -0.4091]
// [-0.6364,    2.3636,   -0.9318,   -0.6591]
// [0.0455,    0.0455,   -0.0227,   -0.1136]
// [0.0455,    0.0455,    0.2273,    0.1364]

Transpose:

var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0]
]);

M.T(); // or also M.transpose()
// [5, 1, -3]
// [-2, 0, 1]
// [2, 0, 5]
// [7, 3, 0]

Cofactor Matrix:

var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0],
    [3, -1, -9, 4]
]);

M.cof();

// [-12, -56, 4, 4]
// [76, 208, 4, 4]
// [-60, -82, -2, 20]
// [-36, -58, -10, 12]

Adjoint:

var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0],
    [3, -1, -9, 4]
]);

M.adj();

//  [ -12, 76, -60, -36 ]
//  [ -56, 208, -82, -58 ]
//  [ 4, 4, -2, -10 ]
//  [ 4, 4, 20, 12 ]

Minor:

// Calculate the determinant when removing the given row and column indexes
var M = new Matrix([
    [5, -2, 2, 7],
    [1, 0, 0, 3],
    [-3, 1, 5, 0],
    [3, -1, -9, 4]
]);

M.minor(0,1); // returns 56

And more matrix operations including:

• Horizontal concatenation: M1.horzcat(M2)
• Vetical concatenation: M1.vertcat(M2)
• Add row: M.addRow(row)
• Add column: M.addColumn(column)
• Remove row: M.deleteRow(index)
• Delete column: M.deleteColumn(index)
• Compare: M1.equals(M2)
• map/apply: M.map(x => x**2), M.apply(x => x**2)
• arange: Matrix.arange(2, 10, 0.5)
• linspace: Matrix.linspace(0, 10, 100)
• reshape: M.reshape([2,3])
• flatten/ravel: M.flatten(), M.ravel()
• diag: M.diag()

Examples

• Solve a system of linear equations using Least Squares method
• Find the roots of a system of equations using Newton-Raphson method