I see that you are facing an issue using the 'Save' and 'Load' buttons in the Phase Plane app.
The ‘Save’ button saves the current custom library to a MAT file while the ‘Load’ button loads a custom library MAT file (the custom library should be one created by the Phase Plane app).
A snapshot of the ‘Save’ functionality is presented below:
You can refer to the documentation of the Phase Plane app to know more about these functionalities: https://www.mathworks.com/matlabcentral/fileexchange/91705-phase-plane-and-slope-field-apps
I hope these resources will help you understanding the ‘Save’ and ‘Load’ buttons in the Phase Plane app.
