Math/matrix.ts

export type RawMatrix = number[][];

export class Matrix {

	rows: number;
	cols: number;
	matrix: RawMatrix;

	static zero(rows: number, cols: number) {
		let matrix: RawMatrix = [];
		for(let i=0; i<rows; i++) {
			matrix.push([]);
			for(let j=0; j<cols; j++) {
				matrix[i].push(0);
			}
		}
		return new Matrix(...matrix);
	}

	constructor(...matrix: RawMatrix) {
		this.matrix = matrix;
		this.rows = matrix.length;
		if(matrix.length == 0) throw Error("Empty matrix");
		this.cols = matrix[0].length;
		for(let i=0; i<matrix.length; i++) {
			if(matrix[i].length !== this.cols) throw Error("Invalid matrix row " + (i+1));
		}
	}

	add(other_matrix: Matrix) {
		if(!(other_matrix.cols == this.cols && other_matrix.rows == this.rows)) throw Error("Other matrix has more or few rows or columns");
		for(let i=0; i<this.matrix.length; i++) {
			for(let j=0; j<this.matrix[i].length; j++) {
				this.matrix[i][j] += other_matrix.matrix[i][j];
			}
		}
		return this;
	}

	sub(other_matrix: Matrix) {
		if(!(other_matrix.cols == this.cols && other_matrix.rows == this.cols)) throw Error("Other matrix has more or few rows or columns");
		for(let i=0; i<this.matrix.length; i++) {
			for(let j=0; j<this.matrix[i].length; j++) {
				this.matrix[i][j] -= other_matrix.matrix[i][j];
			}
		}
		return this;
	}

	mul(other: Matrix | number) {
		if(other instanceof Matrix) {
			if(!(this.cols == other.rows)) throw Error("These matrices cannot be multiplied");
			let final_matrix: RawMatrix = [];
			for(let a_row_i=0; a_row_i<this.matrix.length; a_row_i++) {
				final_matrix.push([]);
				for(let b_col_i=0; b_col_i<other.matrix[0].length; b_col_i++) {
					let sum = 0;
					for(let a_col_b_row_i=0; a_col_b_row_i<this.matrix[0].length; a_col_b_row_i++) {
						sum += this.matrix[a_row_i][a_col_b_row_i] * other.matrix[a_col_b_row_i][b_col_i];
					}
					final_matrix[a_row_i].push(sum);
				}
			}
			return new Matrix(...final_matrix);
		} else {
			for(let i=0; i<this.matrix.length; i++) {
				for(let j=0; j<this.matrix[i].length; j++) {
					this.matrix[i][j] = this.matrix[i][j] * other;
				}
			}
			return this;
		}
	}

	pow(power: number) {
		for(let i=0; i<(power-1); i++)
			this.matrix = this.mul(this).matrix;
		return this;
	}

	invert() {
		this.matrix = this.mul(-1).matrix;
		return this;
	}

	transpose() {
		let new_matrix = Matrix.zero(this.cols, this.rows);
		for(let i=0; i<this.rows; i++) {
			for(let j=0; j<this.cols; j++) {
				new_matrix.matrix[j][i] = this.matrix[i][j];
			}
		}
		return new_matrix;
	}

	eq(other_matrix: Matrix) {
		if(this.rows != other_matrix.rows || this.cols != other_matrix.cols) return false;
		for(let i=0; i<this.rows; i++) {
			for(let j=0; j<this.cols; j++) {
				if(this.matrix[i][j] != other_matrix.matrix[i][j]) return false;
			}
		}
		return true;
	}

}