I have made an example of such an app using MATLAB Online (see the attached file).
Just to walk you through the steps that I took to make the app:
- Create a new app
- Save the app and give it a good name (I named mine answer.mlapp)
- Drag-and-drop a UIAxes component, a discrete knob component, and a button component into the Design View
- Click on the knob and (in the Component Browser on the right side of the screen) change the Items and ItemsData values to 1,2,3,4
- Double-click the button and change the name to "Reset" or to whatever you like
- Switch from Design View to Code View
- Click the red P+ button at the top of the screen to add a private property. This is where you will define the x-values, the vector, and the index for your app. It might look something like this:
properties (Access = private)
xvals = linspace(0,pi*4,80);
vector = sin(linspace(0,pi*4,80));
ind = [10;25;52];
end
- Go back to the Design View, and, in the Component Browser (again, on the right side of the screen) right-click the name of your app (at the top of the Component Browser). Navigate to Callbacks -> Go to startupFcn callback
- Define your callback function so that upon opening the app the entire vector will be plotted. It make look like this:
function startupFcn(app)
plot(app.UIAxes,app.xvals,app.vector)
xlim(app.UIAxes,[0 4*pi])
end
- Return to the Design View and right-click the knob. Navigate to Callbacks -> Go to KnobValueChanged callback
- Define your callback function so that whenever the knob is changed the plot will update to match the index range of the knob value. It may look like this:
function KnobValueChanged(app, event)
value = app.Knob.Value;
if value == 1
plot(app.UIAxes,app.xvals(1:app.ind(1)),app.vector(1:app.ind(1)))
elseif value == 2
plot(app.UIAxes,app.xvals(app.ind(1):app.ind(2)),app.vector(app.ind(1):app.ind(2)))
elseif value == 3
plot(app.UIAxes,app.xvals(app.ind(2):app.ind(3)),app.vector(app.ind(2):app.ind(3)))
else
plot(app.UIAxes,app.xvals(app.ind(3):end),app.vector(app.ind(3):end))
end
% Keep the x-axis limits constant
xlim(app.UIAxes,[0 4*pi])
end
- Return to the Code View again. Now right-click your button and navigate to Callbacks -> Go to ResetButtonPushed callback
- Define your callback to be identical to the startupFcn from above:
function
plot(app.UIAxes,app.xvals,app.vector)
xlim(app.UIAxes,[0 4*pi])
end
