calculate_domain_size.m

this a 3d fdtd code using matlab and it can be used as a reference for other structures. Dear sir,

disp('calculating the number of cells in the problem space');

number_of_spheres = size(spheres,2);
number_of_bricks  = size(bricks,2);

% find the minimum and maximum coordinates of a 
% box encapsulating the objects
number_of_objects = 1;
for i=1:number_of_spheres
    min_x(number_of_objects) = spheres(i).center_x - spheres(i).radius; 
    min_y(number_of_objects) = spheres(i).center_y - spheres(i).radius; 
    min_z(number_of_objects) = spheres(i).center_z - spheres(i).radius; 
    max_x(number_of_objects) = spheres(i).center_x + spheres(i).radius; 
    max_y(number_of_objects) = spheres(i).center_y + spheres(i).radius; 
    max_z(number_of_objects) = spheres(i).center_z + spheres(i).radius; 
    number_of_objects = number_of_objects + 1;
end
for i=1:number_of_bricks
    min_x(number_of_objects) = bricks(i).min_x; 
    min_y(number_of_objects) = bricks(i).min_y; 
    min_z(number_of_objects) = bricks(i).min_z; 
    max_x(number_of_objects) = bricks(i).max_x; 
    max_y(number_of_objects) = bricks(i).max_y; 
    max_z(number_of_objects) = bricks(i).max_z; 
    number_of_objects = number_of_objects + 1;
end

fdtd_domain.min_x = min(min_x);
fdtd_domain.min_y = min(min_y);
fdtd_domain.min_z = min(min_z);
fdtd_domain.max_x = max(max_x);
fdtd_domain.max_y = max(max_y);
fdtd_domain.max_z = max(max_z);

% Determine the problem space boundaries including air buffers 
fdtd_domain.min_x = fdtd_domain.min_x ...
    - dx * boundary.air_buffer_number_of_cells_xn;
fdtd_domain.min_y = fdtd_domain.min_y ...
    - dy * boundary.air_buffer_number_of_cells_yn;
fdtd_domain.min_z = fdtd_domain.min_z ...
    - dz * boundary.air_buffer_number_of_cells_zn;
fdtd_domain.max_x = fdtd_domain.max_x ...
    + dx * boundary.air_buffer_number_of_cells_xp;
fdtd_domain.max_y = fdtd_domain.max_y ...
    + dy * boundary.air_buffer_number_of_cells_yp;
fdtd_domain.max_z = fdtd_domain.max_z ...
    + dz * boundary.air_buffer_number_of_cells_zp;

% Determining the problem space size
fdtd_domain.size_x = fdtd_domain.max_x - fdtd_domain.min_x;
fdtd_domain.size_y = fdtd_domain.max_y - fdtd_domain.min_y;
fdtd_domain.size_z = fdtd_domain.max_z - fdtd_domain.min_z;

% number of cells in x, y, and z directions
nx = round(fdtd_domain.size_x/dx);  
ny = round(fdtd_domain.size_y/dy);
nz = round(fdtd_domain.size_z/dz);

% adjust domain size by snapping to cells
fdtd_domain.size_x = nx * dx;
fdtd_domain.size_y = ny * dy;
fdtd_domain.size_x = nz * dz;

fdtd_domain.max_x = fdtd_domain.min_x + fdtd_domain.size_x;
fdtd_domain.max_y = fdtd_domain.min_y + fdtd_domain.size_y;
fdtd_domain.max_z = fdtd_domain.min_z + fdtd_domain.size_z;

% some frequently used auxiliary parameters 
nxp1 = nx+1;    nyp1 = ny+1;    nzp1 = nz+1;
nxm1 = nx-1;    nxm2 = nx-2;	nym1 = ny-1;
nym2 = ny-2;	nzm1 = nz-1;	nzm2 = nz-2;

% create arrays storing the center coordinates of the cells
fdtd_domain.cell_center_coordinates_x = zeros(nx,ny,nz);
fdtd_domain.cell_center_coordinates_y = zeros(nx,ny,nz);
fdtd_domain.cell_center_coordinates_z = zeros(nx,ny,nz);
for ind = 1:nx
    fdtd_domain.cell_center_coordinates_x(ind,:,:) = ...
        (ind - 0.5) * dx + fdtd_domain.min_x;
end
for ind = 1:ny
    fdtd_domain.cell_center_coordinates_y(:,ind,:) = ...
       (ind - 0.5) * dy + fdtd_domain.min_y;
end
for ind = 1:nz
    fdtd_domain.cell_center_coordinates_z(:,:,ind) = ...
        (ind - 0.5) * dz + fdtd_domain.min_z;
end