% trigfield11.m displays a trig field using several different scales

gridsize = [30 30];                           % number of grid points in x, y
Z        = zeros(gridsize);

m        = 1000;                               % number of Fourier modes

A        = randn(1,m)*sqrt(2/m);                % amplitudes of Fourier modes
phi      = 2 * pi * rand(m,1);                  % random phase
norm     = sqrt(-2*log(rand(m,1)));             % magnitudes of wave numbers
norm     = 0.1*((100000).^rand(m,1));             % magnitudes of wave numbers
theta    = 2 * pi * rand(m,1);                  % arguments of wave numbers
K        = [norm.*cos(theta) norm.*sin(theta)]; % isotropic wave numbers

a        = 0.01;                                   % smallest gridrange
b        = 5;                                  % zoom factor

figure(2)
clf
for v = 1:9,
  subplot(3,3,v)
  gridrange= [0 (a*b^(v-1)) 0 (a*b^(v-1))];     % [xmin xmax ymin ymax]
  [x,y]    = easygrid(gridrange, gridsize);     % matrices of x and y values

  for i=1:gridsize(1),                            % step through grid points
   for j=1:gridsize(2),
    Z(i,j) = A * cos(K*[x(i,j); y(i,j)] + phi); % compute field value at x,y
   end
  end
  mesh(x,y,Z)
  view(-10,20)
end

break

figure(1)
clf
for v = 1:9,
  subplot(3,3,v)
  gridrange= [0 (a*b^(v-1)) 0 (a*b^(v-1))];     % [xmin xmax ymin ymax]
  [x,y]    = easygrid(gridrange, gridsize);     % matrices of x and y values

  for i=1:gridsize(1),                            % step through grid points
   for j=1:gridsize(2),
    Z(i,j) = A * cos(K*[x(i,j); y(i,j)] + phi); % compute field value at x,y
   end
  end
  pcolor(x,y,Z)
end