You only have one axes, and both plot commands are to the same axes, so the 2nd plot replaces the first. You must redraw the sin plot if you want it to display.
My approach would be to have the startup function plot one of them, then update the YData of the line to the desired values inside the callback function for your Previous and Next buttons.
Turn variables a, b, c, and P1 into app properties so you can access them in all your callbacks. See here: https://www.mathworks.com/help/matlab/creating_guis/share-data-across-callbacks-in-app-designer.html
Note that you must specify the target axes for xlabel, ylabel, and title or they will open a new figure window.
Something like this
properties (Access = private)
a % Description
b
c
P1
end
function startupFcn(app)
app.a = 0:0.01:2*pi;
app.b = sin(app.a);
app.c = cos(app.a);
app.P1 = plot(app.UIAxes,app.a,app.b,'DisplayName','Sin Wave');
xlabel(app.UIAxes,'Time1');
ylabel(app.UIAxes,'Range1');
title(app.UIAxes,'Sin Wave Plot')
end
% Button pushed function: NextButton
function NextButtonPushed(app, event)
app.P1.YData = app.c;
title(app.UIAxes,'Cos Wave Plot')
end
% Button pushed function: PreviousButton
function PreviousButtonPushed(app, event)
app.P1.YData = app.b;
title(app.UIAxes,'Sin Wave Plot')
end
