function Z = sampleq(x,y,H,b,c);
% Z = sampleq(x,y,H,b,c)
% Makes a 2-D table of values of
% the quadratic function of 2 variables
%
% z = (1/2)v'*H*v-b'*v+c, v=[x;y]
%
% using outer products.
%
% H is 2x2 symmetric
% b is 2x1
% c is 1x1
%
x = x(:)'; % row vector: 'horizontal' coordinate
y = y(:);  % col vector: 'vertical' coordinate
rw = ones(size(x));
cl = ones(size(y));
Z = 0.5*(H(1,1)*cl*x.^2 + ...
         2*H(1,2)*y*x + ...
         H(2,2)*y.^2*rw) - ...
		 b(1)*cl*x - b(2)*y*rw + c*cl*rw;