% This code plots the solid for part 1 of the Convergence Team Lab
xx = [ -3 : 0.1 : 3];
yy = xx;
sq = sqrt( 9 - yy.^2 );
z1 = ones(size(xx))'*sq;
z2 = abs(xx)'*ones(size(yy));
zz = max(z1 - z2, 0);
surf(xx, yy, zz)
colormap hsv;