Trouble joining to halfs of a plo tto make a full shape.

Hello, I am trying to make multiple shapes and am making the top half fine. When I try to join the shape to a bottom by using surf(x,y,z), hold on, surf(x,y,-z) it plots discs instead of shapes. It works fine on plotting a sphere but not an ellipsoid. Here is the code:

a=linspace(0,1,10);
b=linspace(0,1.5,10);
c=linspace(0,2,10);
a1=ones(22,1)*a;
b1=ones(22,1)*b;
c1=ones(22,1)*c;
z1=real(sqrt(1-x.^2/a1'.^2-y.^2/b1'.^2))
z2=z1*ones(10,22)
subplot(2,2,2)
axis equal,axis square
surf(x,y,z2),hold on
title('b')

aaa=linspace(0,1,10);
bbb=linspace(0,1,10);
ccc=linspace(0,.5,10);
aaa1=ones(22,1)*aaa;
bbb1=ones(22,1)*bbb;
ccc1=ones(22,1)*ccc;
zzz1=.5*sqrt(1-x.^2/aaa1'.^2-y.^2/bbb1'.^2);
zzz2=zzz1*ones(10,22);
subplot(2,2,3);
axis equal
surf(x,y,zzz2)
title('c')

aa=linspace(0,1,10);
bb=linspace(0,1,10);
cc=linspace(0,1.2,10);
aa1=ones(22,1)*aa;
bb1=ones(22,1)*bb;
cc1=ones(22,1)*cc;
zz1=1.2*sqrt(1-x.^2/aa1'.^2-y.^2/bb1'.^2)
zz2=zz1*ones(10,22)
subplot(2,2,4)
axis equal
surf(x,y,zz2),hold on
surf(x,y,-zz2)
title('d')

Any help would be appreciated. Thanks.

[Patrick Kalita]

This code as it is cannot be run because the variable 'x' is not defined.