% code by Colin Macdonald, comments by Ben
% this shows the contour lines of cos(z)

figure(1);

xx = -pi:.01:pi;
yy = -3:.01:3;

[xg,yg] = meshgrid(xx,yy);

Z = xg+1i*yg;

%trick for commenting out a whole paragraph of code
% remove the if statement if you want to see what
% the real and imaginary components look like individually
if ( 1==0)
  figure(1); clf;
  pcolor(xg,yg,real(cos(Z)));
  shading flat;
  hold on;
  [C,H] = contour(xg,yg,real(cos(Z)),[0 0],'k-');
  %for j=1:length(H);
  %  set(H(i),'color',
  colorbar

  figure(2); clf;
  pcolor(xg,yg,imag(cos(Z)));
  shading flat;
  hold on;
  contour(xg,yg,imag(cos(Z)),[0 0], 'k-');
  colorbar
end

figure(3); clf;
pcolor(xg,yg,real(cos(Z)));
shading flat
hold on;
[C,H] = contour(xg,yg,imag(cos(Z)),[0 0], 'k--');
for i=1:length(H)
  set(H(i),'linewidth',3);
end

hold on;
contour(xg,yg,real(cos(Z)), [1,1.1,1.2,1.5], 'k-' );
colorbar;