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

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