function isIdentityMatrix( matrix ) {

    	return equalArray( matrix.elements, [ 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 ] );

    }
Is identity matrix

@param {Matrix4} matrix
@returns {Boolean} Returns true, if parameter is identity matrix