Why I receive error messages “Argument ‘###’ failed validation with error: ####”

Consider a scenario of executing the drawstereonet.m function:

[X,Y] = drawstereonet([10 20 30 40],[50 60 70 80]);
??? Error using ==> drawstereonet at 43
Argument 'AZM' failed validation with error:
Undefined function or method 'ismatrix' for input arguments of type 'double'.

This error results from the fact your MATLAB version does not contain ismatrix() routine. If it is possible, please update the MATLAB to the newest version. Alternatively, you can try to disable the validation routine. In case of example above, by changing line:

p.addOptional('AZM', [], @(x) ismatrix(x) && isnumeric(x) );

to:

p.addOptional('AZM', [], @(x) isnumeric(x) );