This is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License.
GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
Copyright (2014): Md. Enamul Hoque, Department of Physics, Shahjalal University of Science and Technology, Sylhet.