Matrix Arithmetic

矩阵加法、矩阵乘法

* matrix.js

function Matrix(/* Array */a) {
	if (typeof a == "undefined") {
		a = [];
	}
	this._a = a;
	this.row = this._a.length;
	this.col = (typeof this._a[0] == "undefined") ? 0 : this._a[0].length;
}

Matrix.prototype.init = function(/* int */row, /* int */col, val) {
	var i,j;
	
	for (i = 0; i < row; i++) {
		var t = [];
		for (j = 0; j < col; j++) {
			t[j] = val;
		}
		this._a[i] = t;
	}
	this.row = this._a.length;
	this.col = this._a[0].length;
	return this;
};

Matrix.prototype.get = function(/* int */x, /* int */y) {
	return this._a[x][y];
};
Matrix.prototype.set = function(/* int */x, /* int */y, v) {
	this._a[x][y] = v;
	return this;
};

Matrix.prototype.toString = function() {
	var i, j;
	var s = "[";
	
	s += this.get(0, 0);
	for (j = 1; j < this.col; j++) {
		s += ", " + this.get(0, j);
	}
	for (i = 1; i < this.row; i++) {
		s += "\n " + this.get(i, 0);
		for (j = 1; j < this.col; j++) {
			s += ", " + this.get(i, j);
		}
	}
	s += "]";
	return s;
};

Matrix.add = function(/* Matrix */mat1, /* Matrix */mat2) {
	var i, j;
	var mat3 = new Matrix();

	mat3.init(mat1.row, mat2.col, 0);
	for (i = 0; i < mat1.row; i++) {
		for (j = 0; j < mat1.col; j++) {
			mat3.set(i, j, mat1.get(i, j) + mat2.get(i, j));
		}
	}
	return mat3;
};

Matrix.mul = function(/* Matrix */mat1, /* Matrix */mat2) {
	var i, j, k;
	var mat3 = new Matrix();
	var sum;

	mat3.init(mat1.row, mat2.col, 0);
	for (i = 0; i < mat3.row; i++) {
		for (j = 0; j < mat3.col; j++) {
			sum = 0;
			for (k = 0; k < mat1.col; k++) {
				sum += mat1.get(i, k) * mat2.get(k, j);
			}
			mat3.set(i, j, sum);
		}
	}
	return mat3;
}

module.exports = Matrix;

* index.js

var Matrix = require("./matrix");
 
var mat1 = new Matrix([[1,-4],[3,2]]),
	mat2 = new Matrix([[2,2],[2,2]]);
	mat3 = Matrix.add(mat1, mat2);
console.log(mat3.toString());

var mat4 = new Matrix([[0,1],[2,3],[4,5]]),
	mat5 = new Matrix([[6,7,8,9],[0,1,2,3]]),
	mat6;
mat6 = Matrix.mul(mat4, mat5);
console.log(mat6.toString());

[mzh@vultr matrix]$ node index.js?
[3, -2
?5, 4]
[0, 1, 2, 3
?12, 17, 22, 27
?24, 33, 42, 51]