three.js/src/core/Matrix3.js

THREE.Matrix3 = function () {

	this.m = [];

};

THREE.Matrix3.prototype = {

	constructor: THREE.Matrix3,

	transpose: function () {

		var tmp, m = this.m;

		tmp = m[1]; m[1] = m[3]; m[3] = tmp;
		tmp = m[2]; m[2] = m[6]; m[6] = tmp;
		tmp = m[5]; m[5] = m[7]; m[7] = tmp;

		return this;

	},

	transposeIntoArray: function ( r ) {

		var m = this.m;

		r[ 0 ] = m[ 0 ];
		r[ 1 ] = m[ 3 ];
		r[ 2 ] = m[ 6 ];
		r[ 3 ] = m[ 1 ];
		r[ 4 ] = m[ 4 ];
		r[ 5 ] = m[ 7 ];
		r[ 6 ] = m[ 2 ];
		r[ 7 ] = m[ 5 ];
		r[ 8 ] = m[ 8 ];

		return this;

	}

};