contour matrix empty in contourf

Hi:

I have a X,Y,Z matrix, and use command [xc,yc]=contourf(new_X,new_Y,new_Z); to plot a contour plot.

The xc is empty, but it can be seen in 'new_Z', it is not empty and have a wide range of variation.

is there any problem with my operation?

Thanks!

Yu

[Walter Roberson]

This seems to be related to the fact that the range of values is your new_Z is so high that with the default settings, everything falls into one contour. If you ask for at least 15 contour intervals then you get a non-empty first output.

[Yu Li]

Hi Walter:

Thanks for your reply.

could you please explain what do you mean by 'ask for at least 15 contour intervals'?

Thanks!

Yu

[Walter Roberson]

NumLevels = 15;
[M, c] = contourf(new_X, new_Y, new_Z, NumLevels);

My tests with your data shows that c comes out empty if the number of levels is 14 or less (default is 10.)