Always Error is seen

It always tells me that Z is not matrix

[dpb]

Well then, it must not be.

How are we supposed to do anything from that cryptic statement alone???

[Abhaya]

There might be a problem with variable name. Try to delete the workspace and run the program again.

Answer 1

[Walter Roberson]

Most likely, you are using surf() or contour() and the complaint is that Z is not at least a 2 x 2 matrix.

The most common cause for this problem is if you have vectors of x, y, and z, and try to surf() or contour() the vectors . If you have vectors x y and z, then you need to use scatteredInterpolant to produce a gridded Z to plot.

The second most common cause of this problem is if you have vectors x and y that are the same size and orientation and use them to calculate z... getting out a vector z. If you want to calculate for each independent pair of x and y, you need to make sure that the vectors are different orientation, such as x(:).^2 - 2.*y(:).'

The third most common cause of this problem is if you accidentally use the / operation where you need the ./ operation