Using meshgrid then contourf but image does not reach out to the positive extent of axis (on right, +, and on top,+)

[Thompson, Robert M - (rmt1)]

The left and bottom, or the negative extents, do show the most negative extent of the axis.

The output image's axes go -15, -10, -5, 0, 5, 10, but no 15.

I put a tape measure against the screen, and the actual image itself does not reach out to 15.

Code:

[X,Y]=meshgrid(-15:pixelsize:15,-15:pixelsize:15);

Z=griddata(x,y,z,X,Y);

zmin=floor(min(z(:)));

zmax=ceil(max(z(:)));

zinc=(zmax-zmin)/gradients;

zlevs=zmin:zinc:zmax;

v=[-5.00:0.1:+5.00];

[C,h]=contourf(X,Y,Z,zlevs);

Ideas?

Thank you,

Robert