% iidfield2.m generates, smooths, and graphs a matrix of iid variables

gridsize = [40 40];             
[x,y]    = easygrid([0 10 0 10], gridsize); % [xmin xmax ymin ymax]

% Uniformly distributed field
Z        = rand(gridsize);                % Z is a matrix of Uniform(0,1)'s
m        = 0.5;                           % the mean for Uniform(0,1)
hmin     = 0;                             % horizontal range minimum
hmax     = 1;                             % horizontal range maximum

% Normally distributed field
%Z        = randn(gridsize);               % Z is a matrix of N(0,1)'s
%m        = 0.0;                           % the mean for N(0,1)
%hmin     = -2;                            % horizontal range minimum
%hmax     = 2;                             % horizontal range maximum

h = [[0 .125 0]; [.125 .5 .125]; [0 .125 0]]; % weights for averaging
%h = fspecial('gaussian',[5 5],1);        % a different filter for averaging

for i=1:100,                              % smooth up to 100 times

  subplot(3,2,1)
  mesh(x,y,Z)
  view(-10,50)
  xlabel('Horizontal');
  ylabel('Vertical');
  zlabel('Intensity');
  title('Surface plot');

  subplot(3,2,2)
  mesh(x,y,Z)
  view(80,50)
  xlabel('Horizontal');
  ylabel('Vertical');
  zlabel('Intensity');
  title('Surface plot');

  subplot(3,2,3)
  contour(x,y,Z,20)
  title('Contour plot')

  subplot(3,2,4)
  pcolor(x,y,Z)
  shading flat
  title('Grayscale plot')

  subplot(3,2,5)
  hist(reshape(Z,1,prod(gridsize)))
  V = axis;                               % get current xmin,xmax,ymin,ymax
  V(1)=hmin; V(2)=hmax;                   % set horizontal range
  axis(V);                                % re-set axis limits
  title('Histogram of field values')

  Z = conv2(Z-m,h,'same')+m;  % smooth the values of Z
                                  % conv2 uses zeros on the edge, so we
                                  % subtract and add back in the mean m

  drawnow;                    % display image now, not when the program is done
  pause                       % press a key to continue, Ctrl-C to break
end