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CACmb/src/subroutines.f90

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module subroutines
use parameters
use functions
use box
implicit none
integer :: allostat, deallostat
public
contains
!This subroutine is just used to break the code and exit on an error
subroutine read_error_check(para, loc)
integer, intent(in) :: para
character(len=100), intent(in) :: loc
if (para > 0) then
print *, "Read error in ", trim(loc), " because of ", para
stop "Exit with error"
end if
end subroutine
subroutine matrix_inverse(a, n, a_inv)
integer :: i, j, k, piv_loc
integer, intent(in) :: n
real(kind = dp) :: coeff, sum_l, sum_u
real(kind = dp), dimension(n) :: b, x, y, b_piv
real(kind = dp), dimension(n, n) :: l, u, p
real(kind = dp), dimension(n, n), intent(in) :: a
real(kind = dp), dimension(n, n), intent(out) :: a_inv
real(kind = dp), allocatable :: v(:), u_temp(:), l_temp(:), p_temp(:)
l(:, :) = identity_mat(n)
u(:, :) = a(:, :)
p(:, :) = identity_mat(n)
!LU decomposition with partial pivoting
do j = 1, n-1
allocate(v(n-j+1), stat = allostat)
if(allostat /=0 ) then
print *, 'Fail to allocate v in matrix_inverse'
stop
end if
v(:) = u(j:n, j)
if(maxval(abs(v)) < lim_zero) then
print *, 'Fail to inverse matrix', a
stop
end if
piv_loc = maxloc(abs(v), 1)
deallocate(v, stat = deallostat)
if(deallostat /=0 ) then
print *, 'Fail to deallocate v in matrix_inverse'
stop
end if
!partial pivoting
if(piv_loc /= 1) then
allocate( u_temp(n-j+1), p_temp(n), stat = allostat)
if(allostat /=0 ) then
print *, 'Fail to allocate p_temp and/or u_temp in matrix_inverse'
stop
end if
u_temp(:) = u(j, j:n)
u(j, j:n) = u(piv_loc+j-1, j:n)
u(piv_loc+j-1, j:n) = u_temp(:)
p_temp(:) = p(j, :)
p(j, :) = p(piv_loc+j-1, :)
p(piv_loc+j-1, :) = p_temp(:)
deallocate( u_temp, p_temp, stat = deallostat)
if(deallostat /=0 ) then
print *, 'Fail to deallocate p_temp and/or u_temp in matrix_inverse'
stop
end if
if(j > 1) then
allocate( l_temp(j-1), stat = allostat)
if(allostat /= 0) then
print *, 'Fail to allocate l_temp in matrix_inverse'
stop
end if
l_temp(:) = l(j, 1:j-1)
l(j, 1:j-1) = l(piv_loc+j-1, 1:j-1)
l(piv_loc+j-1, 1:j-1) = l_temp(:)
deallocate( l_temp, stat = deallostat)
if(deallostat /=0 ) then
print *, 'Fail to deallocate l_temp in matrix_inverse'
stop
end if
end if
end if
!LU decomposition
do i = j+1, n
coeff = u(i, j)/u(j, j)
l(i, j) = coeff
u(i, j:n) = u(i, j:n)-coeff*u(j, j:n)
end do
end do
a_inv(:, :) = 0.0_dp
do j = 1, n
b(:) = 0.0_dp
b(j) = 1.0_dp
b_piv(:) = matmul(p, b)
!Now we have LUx = b_piv
!the first step is to solve y from Ly = b_piv
!forward substitution
do i = 1, n
if(i == 1) then
y(i) = b_piv(i)/l(i, i)
else
sum_l = 0
do k = 1, i-1
sum_l = sum_l+l(i, k)*y(k)
end do
y(i) = (b_piv(i)-sum_l)/l(i, i)
end if
end do
!then we solve x from ux = y
!backward subsitution
do i = n, 1, -1
if(i == n) then
x(i) = y(i)/u(i, i)
else
sum_u = 0
do k = i+1, n
sum_u = sum_u+u(i, k)*x(k)
end do
x(i) = (y(i)-sum_u)/u(i, i)
end if
end do
!put x into j column of a_inv
a_inv(:, j) = x(:)
end do
return
end subroutine matrix_inverse
subroutine parse_ori_vec(ori_string, ori_vec)
!This subroutine parses a string to vector in the format [ijk]
character(len=8), intent(in) :: ori_string
real(kind=dp), dimension(3), intent(out) :: ori_vec
integer :: i, ori_pos, stat
ori_pos=2
do i = 1,3
if (ori_string(ori_pos:ori_pos) == '-') then
ori_pos = ori_pos + 1
read(ori_string(ori_pos:ori_pos), *, iostat=stat) ori_vec(i)
if (stat>0) STOP "Error reading orientation value"
ori_vec(i) = -ori_vec(i)
ori_pos = ori_pos + 1
else
read(ori_string(ori_pos:ori_pos), *, iostat=stat) ori_vec(i)
if(stat>0) STOP "Error reading orientation value"
ori_pos=ori_pos + 1
end if
end do
return
end subroutine parse_ori_vec
recursive subroutine parse_pos(i, pos_string, pos)
!This subroutine parses the pos command allowing for command which include inf
integer, intent(in) :: i !The dimension of the position
character(len=100), intent(in) :: pos_string !The position string
real(kind=dp), intent(out) :: pos !The output parsed position value
integer :: iospara
real(kind=dp) :: rand, rone, rtwo
character(len=100) :: cone, ctwo
iospara = 0
if(trim(adjustl(pos_string)) == 'inf') then
pos=box_bd(2*i)
else if(trim(adjustl(pos_string)) == '-inf') then
pos=box_bd(2*i-1)
else if (trim(adjustl(pos_string)) == 'rand') then
call random_number(rand)
pos = (box_bd(2*i)-box_bd(2*i-1))*rand + box_bd(2*i-1)
else if (index(pos_string,'rand')>0) then
call random_number(rand)
cone = pos_string(index(pos_string, '[')+1:index(pos_string,':')-1)
call parse_pos(i, cone, rone)
ctwo = pos_string(index(pos_string, ':')+1:index(pos_string,']')-1)
call parse_pos(i, ctwo, rtwo)
pos = (rtwo - rone)*rand + rone
else if ((index(pos_string,'-') > 0).and.(index(pos_string,'inf')>0)) then
!Now extract the number we are reducing from infinity
if(index(pos_string,'inf') < index(pos_string,'-')) then
read(pos_string(index(pos_string,'-')+1:), *, iostat=iospara) pos
else
read(pos_string(1:index(pos_string,'-')-1), *, iostat=iospara) pos
end if
pos = box_bd(2*i) - pos
else if ((index(pos_string,'+') > 0).and.(index(pos_string,'inf')>0)) then
!Now extract the number we are reducing from infinity
if(index(pos_string,'inf') < index(pos_string,'+')) then
read(pos_string(index(pos_string,'+')+1:), *, iostat=iospara) pos
else
read(pos_string(1:index(pos_string,'+')-1), *, iostat=iospara) pos
end if
pos = box_bd(2*i-1) + pos
else if ((index(pos_string,'*') > 0).and.(index(pos_string,'inf')>0)) then
!Now extract the number we are reducing from infinity
if(index(pos_string,'inf') < index(pos_string,'*')) then
read(pos_string(index(pos_string,'*')+1:), *, iostat=iospara) pos
else
read(pos_string(1:index(pos_string,'*')-1), *, iostat=iospara) pos
end if
pos = (box_bd(2*i)-box_bd(2*i-1))*pos + box_bd(2*i-1)
else
read(pos_string, *, iostat=iospara) pos
end if
if (iospara > 0) then
print *, "Error reading position argument ", trim(adjustl(pos_string)), ". Please reformat and try again."
end if
end subroutine parse_pos
subroutine heapsort(a)
integer, intent(in out) :: a(0:)
integer :: start, n, bottom
real :: temp
n = size(a)
do start = (n - 2) / 2, 0, -1
call siftdown(a, start, n);
end do
do bottom = n - 1, 1, -1
temp = a(0)
a(0) = a(bottom)
a(bottom) = temp;
call siftdown(a, 0, bottom)
end do
end subroutine heapsort
subroutine siftdown(a, start, bottom)
integer, intent(in out) :: a(0:)
integer, intent(in) :: start, bottom
integer :: child, root
real :: temp
root = start
do while(root*2 + 1 < bottom)
child = root * 2 + 1
if (child + 1 < bottom) then
if (a(child) < a(child+1)) child = child + 1
end if
if (a(root) < a(child)) then
temp = a(child)
a(child) = a (root)
a(root) = temp
root = child
else
return
end if
end do
end subroutine siftdown
subroutine apply_periodic(r)
!This function checks if an atom is outside the box and wraps it back in. This is generally used when some
!kind of displacement is applied but the simulation cell is desired to be maintained as the same size.
real(kind=dp), dimension(3), intent(inout) :: r
integer :: j
real(kind=dp) ::box_len
do j = 1, 3
box_len = box_bd(2*j) - box_bd(2*j-1)
if (r(j) > box_bd(2*j)) then
r(j) = r(j) - box_len
else if (r(j) < box_bd(2*j-1)) then
r(j) = r(j) + box_len
end if
end do
end subroutine
subroutine build_cell_list(numinlist, r_list, rc_off, cell_num, num_in_cell, cell_list, which_cell)
!This subroutine builds a cell list based on rc_off
!----------------------------------------Input/output variables-------------------------------------------
integer, intent(in) :: numinlist !The number of points within r_list
real(kind=dp), dimension(3,numinlist), intent(in) :: r_list !List of points to be used for the construction of
!the cell list.
real(kind=dp), intent(in) :: rc_off ! Cutoff radius which dictates the size of the cells
integer, dimension(3), intent(inout) :: cell_num !Number of cells in each dimension.
integer, allocatable, intent(inout) :: num_in_cell(:,:,:) !Number of points within each cell
integer, allocatable, intent(inout) :: cell_list(:,:,:,:) !Index of points from r_list within each cell.
integer, dimension(3,numinlist), intent(out) :: which_cell !The cell index for each point in r_list
!----------------------------------------Begin Subroutine -------------------------------------------
integer :: i, j, cell_lim, c(3)
real(kind=dp) :: box_len(3)
integer, allocatable :: resize_cell_list(:,:,:,:)
!First calculate the number of cells that we need in each dimension
do i = 1,3
box_len(i) = box_bd(2*i) - box_bd(2*i-1)
cell_num(i) = int(box_len(i)/(rc_off/2))+1
end do
!Initialize/allocate variables
cell_lim = 10
allocate(num_in_cell(cell_num(1),cell_num(2),cell_num(3)), cell_list(cell_lim, cell_num(1), cell_num(2), cell_num(3)))
!Now place points within cell
do i = 1, numinlist
!c is the position of the cell that the point belongs to
do j = 1, 3
c(j) = int((r_list(j,i)-box_bd(2*j-1))/(rc_off/2)) + 1
end do
!Place the index in the correct position, growing if necessary
num_in_cell(c(1),c(2),c(3)) = num_in_cell(c(1),c(2),c(3)) + 1
if (num_in_cell(c(1),c(2),c(3)) > cell_lim) then
allocate(resize_cell_list(cell_lim+10,cell_num(1),cell_num(2),cell_num(3)))
resize_cell_list(1:cell_lim, :, :, :) = cell_list
resize_cell_list(cell_lim+1:, :, :, :) = 0
call move_alloc(resize_cell_list, cell_list)
end if
cell_list(num_in_cell(c(1),c(2),c(3)),c(1),c(2),c(3)) = i
which_cell(:,i) = c
end do
return
end subroutine build_cell_list
end module subroutines