clf; clear;

xmin = -2; xmax = 4; xmesh = 100; 
xdel = (xmax-xmin)/xmesh; x = xmin+xdel/2:xdel:xmax-xdel/2;
ymin = -3; ymax = 3; ymesh = 100;
ydel = (ymax-ymin)/ymesh; y = ymin+ydel/2:ydel:ymax-ydel/2;
a = [-5 55];
z = ones(xmesh, ymesh);

for i = 1:xmesh,
  for j = 1:ymesh,
    z(i,j) = exp( -(x(i)-1)^2/2 - y(j)^2/2 ) / 2 / pi;
  end;
end;
subplot(1,2,1);
surfl(x,y,z); colormap(pink); shading interp;
sxlabel ('\18\times\italic v_x'); 
stext(-3.3, 6, 0, '\18\times\italic v_z');
stext(-3.3, 5, 0.24, '\18\times\italic f');
set(gca, 'ZTickLabel', [], 'ZTick', []);
view (a); axis square; grid off;

for i = 1:xmesh,
  for j = 1:ymesh,
    z(i,j) = exp( -(x(i)-1)^2/2 - y(j)^2/2 - 2 * 0.3 * (x(i)-1) * y(j) ) ...
	/ 2 / pi;
  end;
end;
subplot(1,2,2);
surfl(x,y,z); colormap(pink); shading interp;
sxlabel ('\18\times\italic v_x'); 
stext(-3.3, 6, 0, '\18\times\italic v_z');
stext(-3.3, 5, 0.24, '\18\times\italic f');
set(gca, 'ZTickLabel', [], 'ZTick', []);
view (a); axis square; grid off;

print -deps chap.eps;
