quantum-espresso/PW/eqvect.f90

34 lines
1.1 KiB
Fortran

!
! Copyright (C) 2001 PWSCF group
! This file is distributed under the terms of the
! GNU General Public License. See the file `License'
! in the root directory of the present distribution,
! or http://www.gnu.org/copyleft/gpl.txt .
!
!-----------------------------------------------------------------------
logical function eqvect (x, y, f)
!-----------------------------------------------------------------------
!
! This function test if the difference between two tridimensional
! vectors is an integer. The presence of a fractionary translation
! may be required. (f)
!
! Last revision June 1997 (PG+SdG)
!
USE kinds
implicit none
real(kind=DP) :: x (3), y (3), f (3)
! input: input vector
! input: second input vector
! input: fractionary translation
real(kind=DP) :: accep
! acceptance parameter
parameter (accep = 1.0d-5)
!
eqvect = abs (x (1) - y (1) - f (1) - nint (x (1) - y (1) - f (1) &
) ) .lt.accep.and.abs (x (2) - y (2) - f (2) - nint (x (2) &
- y (2) - f (2) ) ) .lt.accep.and.abs (x (3) - y (3) - f (3) &
- nint (x (3) - y (3) - f (3) ) ) .lt.accep
return
end function eqvect