mirror of https://gitlab.com/QEF/q-e.git
152 lines
4.3 KiB
Fortran
152 lines
4.3 KiB
Fortran
!
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! Copyright (C) 2001 PWSCF group
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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!-----------------------------------------------------------------------
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subroutine set_fft_dim
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!-----------------------------------------------------------------------
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! This routine computes the dimensions of the minimum FFT grid
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! compatible with the input cut-off
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!
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! NB: The values of nr1, nr2, nr3 are computed only if they are not
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! given as input parameters. Input values are kept otherwise.
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!
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use pwcom
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implicit none
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integer, parameter :: nmax = 1000
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! an unreasonably big number for a FFT grid
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logical :: allowed
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! external function which sets the allowed fft dimension
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!
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! the values of nr1, nr2, nr3 are computed only if they are not given
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! as input parameters
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!
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if (nr1.eq.0) then
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!
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! estimate nr1 and check if it is an allowed value for FFT
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!
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nr1 = int (2 * sqrt (gcutm) * sqrt (at (1, 1) **2 + at (2, 1) &
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**2 + at (3, 1) **2) ) + 1
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10 continue
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if (nr1.gt.nmax) call error ('allocate_fft', 'nr1 > nmax ?!? ', &
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nr1)
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if (allowed (nr1) ) goto 15
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nr1 = nr1 + 1
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goto 10
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else
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if (.not.allowed (nr1) ) call error ('set_fft_dim', &
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'input nr1 value not allowed', 1)
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endif
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15 continue
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!
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! here we compute nr1s if it is not in input
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!
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if (nr1s.eq.0) then
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!
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! estimate nr1 and check if it is an allowed value for FFT
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!
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if (doublegrid) then
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nr1s = 2 * int (sqrt (gcutms) * sqrt (at (1, 1) **2 + at (2, 1)**2 &
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+ at (3, 1) **2) ) + 1
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else
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nr1s = nr1
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endif
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11 continue
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if (nr1s.gt.nmax) call error ('allocate_fft', 'nr1s > nmax ?!? ', nr1s)
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if (allowed (nr1s) ) goto 16
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nr1s = nr1s + 1
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goto 11
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endif
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16 continue
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!
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if (nr2.eq.0) then
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!
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! estimate nr1 and check if it is an allowed value for FFT
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!
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nr2 = int (2 * sqrt (gcutm) * sqrt (at (1, 2) **2 + at (2, 2) &
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**2 + at (3, 2) **2) ) + 1
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20 continue
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if (nr2.gt.nmax) call error ('allocate_fft', 'nr2 > nmax ?!? ', nr2)
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if (allowed (nr2) ) goto 25
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nr2 = nr2 + 1
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goto 20
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else
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if (.not.allowed (nr2) ) call error ('set_fft_dim', &
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'input nr2 value not allowed', 2)
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endif
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25 continue
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!
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! here we compute nr2s if it is not in input
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!
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if (nr2s.eq.0) then
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!
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! estimate nr1 and check if it is an allowed value for FFT
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!
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if (doublegrid) then
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nr2s = 2 * int (sqrt (gcutms) * sqrt (at (1, 2) **2 + at (2, 2) **2 &
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+ at (3, 2) **2) ) + 1
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else
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nr2s = nr2
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endif
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21 continue
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if (nr2s.gt.nmax) call error ('allocate_fft', 'nr2s > nmax ?!? ', nr2s)
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if (allowed (nr2s) ) goto 26
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nr2s = nr2s + 1
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goto 21
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endif
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26 continue
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!
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if (nr3.eq.0) then
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!
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! estimate nr3 and check if it is an allowed value for FFT
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!
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nr3 = int (2 * sqrt (gcutm) * sqrt (at (1, 3) **2 + at (2, 3) &
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**2 + at (3, 3) **2) ) + 1
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30 continue
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if (nr3.gt.nmax) call error ('allocate_fft', 'nr3 > nmax ?!? ', nr3)
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if (allowed (nr3) ) goto 35
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nr3 = nr3 + 1
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goto 30
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else
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if (.not.allowed (nr3) ) call error ('set_fft_dim', &
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'input nr3 value not allowed', 3)
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endif
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35 continue
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!
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! here we compute nr3s if it is not in input
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!
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if (nr3s.eq.0) then
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!
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! estimate nr1 and check if it is an allowed value for FFT
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!
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if (doublegrid) then
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nr3s = 2 * int (sqrt (gcutms) * sqrt (at (1, 3) **2 + at (2, &
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3) **2 + at (3, 3) **2) ) + 1
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else
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nr3s = nr3
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endif
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31 continue
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if (nr3s.gt.nmax) call error ('allocate_fft', 'nr3s > nmax ?!? ', &
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&nr3s)
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if (allowed (nr3s) ) goto 36
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nr3s = nr3s + 1
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goto 31
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endif
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36 continue
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!
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if (nr1s.gt.nr1.or.nr2s.gt.nr2.or.nr3s.gt.nr3) then
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write (6, * ) nr1s, nr2s, nr3s, nr1, nr2, nr3
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call error ('set_fft', 'smooth grid larger than big grid', 1)
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endif
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!
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if (.not.doublegrid.and. ( &
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nr1s.ne.nr1.or.nr2s.ne.nr2.or.nr3s.ne.nr3) ) &
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call error ('set_fft', 'grids and dual are inconsistent', 2)
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return
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end subroutine set_fft_dim
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