%script to view a parabola (I think it is a parabola, anyway)
%JRA, April 12, 2002

%grid size
nx = 50;
ny = nx;
%grid range
mine=-10;
maxe=10;
minn = mine;
maxn = maxe;

%set up the easting and northing grids
estep = abs((mine-maxe)/nx);
nstep = abs((minn-maxn)/ny);
ee = [mine:estep:maxe];
nn = [minn:nstep:maxn];
e= meshgrid(ee,ee);
n= meshgrid(nn,nn)';

%here are the shape parameters.  If a=b, then it is symmetric, a not equal b is assymmetric
a=1;
b=1;
c=200;
%here is the action.  Note that we have to subtract from c because other wise it is a bowl.
h=c-(a.*e.^2+b.*n.^2);

%color image map
figure(1)
clf
plot(0,0,'k+')
hold on
imagesc(ee',nn',h)
xlabel('easting')    
ylabel('northing')   
title('tester')
axis equal
colorbar

%surface
figure(2)
clf
surfl(ee,nn,h)
shading interp
colormap(copper)
hold on
view(-30,60)
xlabel('easting')    
ylabel('northing')
zlabel('elevation')   
title('tester')