The first argument must be a valid axes handle
Posted: Sat Jun 17, 2017 6:55 am
The first argument must be a valid axes handle
ax = gca
returns the current axes (or standalone visualization) in the current figure. Use ax to get and set properties of the current axes. If there are no axes or charts in the current figure, then gca creates a Cartesian axes object.
https://www.mathworks.com/help/matlab/ref/gca.html
solution,
check the first argument.