Initial commit of the AENET code.

!-----------------------------------------------------------------------
!                mathematical and physical constants
!-----------------------------------------------------------------------
!+ This file is part of the AENET package.
!+
!+ Copyright (C) 2012-2016 Nongnuch Artrith and Alexander Urban
!+
!+ This program 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, or
!+ (at your option) any later version.
!+
!+ This program is distributed in the hope that it will be useful, but
!+ WITHOUT ANY WARRANTY; without even the implied warranty of
!+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 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/>.
!-----------------------------------------------------------------------
! 2013-12-30 Nongnuch Artrith (NA), Alexander Urban (AU)
!-----------------------------------------------------------------------
module constants

  implicit none

  double precision, parameter, public :: PI = 3.141592653589793d0

end module constants