latice boltzman streaming in matlab

latice.m

#!/usr/bin/env octave
% kate: hl octave; line-numbers on; space-indent on; indent-mode cstyle;
more off;
global data;
function move(irow, icol)
  global data;
  [srow,scol] = size(data);
  vrow = 1:srow;
  vcol = 1:scol;
  if(icol < 0) 
    vcol = fliplr(vcol);
  end
  if(irow < 0)
    vrow = fliplr(vrow);
  end
  
  % deal with corner data(srow,scol)
  data(srow,scol) = data(mod(srow-1+irow+srow,srow)+1,mod(scol-1+icol+scol,scol)+1);
  % deal with inner cells  
  for col=vcol # x
    for row=vrow # y
      nrow = mod(row-1+irow+srow,srow)+1;
      ncol = mod(col-1+icol+scol,scol)+1;
      if(row == 1)
        % printf("%d->%d\n", col,ncol);
      end
      data(row,col) = data(nrow,ncol);
    end
  end  
endfunction


cycles=2000;
N = 3;
runs=N*cycles
Nd = N + 1;
% a = 1:N;
% field = ones(3,1)*a;
% field = a'*a;
data_start  = zeros(Nd,Nd);
%data(1:N,1:N) = field
%data_start(1,1) = 1 % initialize one element
%data_start(1,1:N) = 1;
data_start(1:N,1:N) = rand(N,N)
scol = N; srow = N; % size of the physical grid
irow = 1; % increment
icol = 1; 
% version move % % % % % % % % % % % % % % % % %
data = data_start;
tic
for r=1:runs
  % ghost cells
  % copy edge top to bottom
  data(Nd,1:N) = data(1,1:N);
  % copy edge left to right
  data(1:N,Nd) = data(1:N,1);
  move(irow,icol);
  for col=1:scol % x
    for row=1:srow % y
      % heavy grid point manipulation
      val = data(row,col);
      if(val ~= 0)
        val += 1;
      end
      data(row,col) = mod(val,200);
    end
  end
end
toc
data(1:N,1:N)
% version index % % % % % % % % % % % % % % % %
data = data_start;
data_proj = data_start(1:N,1:N);
orow = 0; % offset row
ocol = 0; % offset col
tic
for r=1:runs
  % define offset
  orow = mod(orow+irow,srow);
  ocol = mod(ocol+icol,scol);
  for col=1:scol # x
    for row=1:srow # y
      % compute index
      nrow = mod(row-1+orow+srow,srow)+1;
      ncol = mod(col-1+ocol+scol,scol)+1;
      % heavy grid point manipulation
      val = data(nrow,ncol);
      if(val ~= 0)
        val += 1;
      end
      data(nrow,ncol) = mod(val,200);
      % data_proj(row,col) = data(nrow,ncol);
    end
  end
end
toc
% data_proj
data(1:N,1:N)