matrmath

matrmath

A library for performing matrix operations.

Installation

npm install matrmath

Usage

Utilize the functions in this library for performing matrix operations.

For example, compute the diagonal difference of a square (n x n) matrix:

const mtr = require("matrmath");

let diff = mtr.diagonalDiff([
    [2, 5, 3],
    [4, 6, 1],
    [7, 8, 9]
]);

console.log(diff);
// |(2+6+9) - (3+6+7)| = |17-16| = 1

Or compute a matrix in reduced row echelon form:

const mtr = require("matrmath");

let reduced = mtr.rowReduce([
    [5, 8, 2],
    [3, 5, 3],
    [6, 4, 9]
]);

console.log(reduced);
// [ [ 1, 0, 0 ], [ 0, 1, 0 ], [ 0, 0, 1 ] ]

Config

rowReduce(M)

Transform a matrix in-place and return the reduced row-echelon form of a matrix. Row replacement is achieved through Gaussian Elimination.

• M - number[][] - A 2-dimensional array.
• square - boolean - Optional boolean parameter to specify if the matrix is square (ie 3x3, 4x4 etc).

diagonalDiff(M)

Return the diagonal difference of a square. The diagonal difference is the absolute value of the left diagonal minus the right diagonal in a square matrix.

• M - number[][] | number[] - A 2-dimensional array, or optionally 1D array.
• is2D - boolean - Optional boolean parameter to specify if the matrix is 1D instead of 2D.
• debug - boolean - Optional boolean parameter to output the lib object with items used in computations.

isSquare(M)

Check whether a 2D or 1D matrix is square. That is the number of rows equals the number of columns in a n x m layout where n = rows and m = columns and n must equal m.

• M - number[][] | number[] - A 2D or 1D array, or optionally 1D array.
• is2D - boolean - Optional boolean parameter to specify if the matrix is 1D instead of 2D.

det(M)

Calculate the determinant of a matrix.

• M - number[][] - A 2-dimensional array.

isIndependent(M)

Calculate whether a square matrix is linearly independent. If the determinant of a matrix is not equal to 0, its linearly independent.

• M - number[][] - A 2-dimensional array.

isDependent(M)

Calculate whether a square matrix is linearly dependent. Meaning its determinant equals 0.

• M - number[][] - A 2-dimensional array.

Tests

npm run test

Todo

• Add a utility for transforming points in R^n to R^n. In other words, transform a set of points in some space (R2) to points in (R3). Have a initial input matrix and a transformation matrix as parameters to output the points after being multiplied by the transformation matrix.

Resources

• Reduced Row Echelon Form (JavaScript) - code example by rosettacode.
• Determinant - JavaScript - code example by rosettacode.
• substrack/rref - library for row reducing based on rosettacode example.