How to restrict the angle a cylinder is defined over

If you have a cylinder generated by the following code how would you define is so that the cylinder is restricted to certain angles such as between 0 and pi, thanks

    [x,y,z]=cylinder([0,7,7,0],100);

    z([1,2],:)=0;

    z([3,4],:)=0.1;

    surf(x,y,z);

    axis equal

Answer 1

[Matt J]

One way,

    [x,y,z]=cylinder([0,7,7,0],100);
    z([1,2],:)=0;
    z([3,4],:)=0.1;

    [theta,rho] = cart2pol(x,y);

    keep=(theta<=pi & theta>=0) | rho==0;

    z(~keep)=nan;

    surf(x,y,z);
    axis equal

[Jonathan Bird]

Thanks, the trouble is I want all the internal bit as well not just a ring at the edge

[Matt J]

I updated my code. Try it again. This is what I get:

Answer 2

[Star Strider]

Another option:

[x,y,z]=cylinder([0,7,7,0],100);
cidx = 1:ceil(size(x,2)*(pi/(2*pi)));                   % Scale Column Index By Fractions Of ‘2*pi’
z([1,2],:)=0;
z([3,4],:)=0.1;

surf(x(:,cidx) ,y(:,cidx) ,z(:,cidx));
axis equal
shading interp