Lev - why in your SliderValueChanged callback are you overwriting the Slider with its value? I suggest that you remove this function (or at least the code inside of it)
function SliderValueChanged(app, event)
% app.Slider = app.Slider.Value; % <----- this isn't necessary and is dangerous!
end
As for the error, it is telling you that you are trying to index into an array with something other than a positive integer or (0 or 1) logical value. I suspect that the slider value is NOT an integer so you will need to ask your self how to convert this number into a valid index for the arrays. For example, your code might look like
function GPSMenuSelected(app, event)
gps1=[app.x;app.y];
plot(app.UIAxes,app.x,app.y,'LineWidth',2);
hold on
sliderValue = ceil(app.Slider.Value); % <--- round up to the nearest integer
if sliderValue >= 1 && sliderValue <= length(app.x)
plot(app.UIAxes,app.x(sliderValue),app.y(sliderValue),'b--o',...
'LineWidth',6);
end
hold off
end
I don't know if that is valid for you so please validate before trying it out.
