Xlim error in App designer

% Value changing function: STARTKnob_2
function STARTKnob_2ValueChanging(app, event)
arguments
    app
    event.Value(1,1) {mustBeNumeric}=0 
end
app.StartYear = event.Value;
if app.StartYear>app.StopYear-1 %checks the increasing-xrule
    app.StopYear=min([app.StartYear+1,app.STOPKnob.Limits(2)]);
    app.STOPKnob.Value=app.StopYear; %rotate the stop knob
    app.StartYear=app.StopYear-1;
    app.STARTKnob_2.Value=app.StartYear;
end
app.plotData();

end
% Value changing function: STOPKnob
function STOPKnobValueChanging(app, event)
arguments
    app
    event.Value(1,1) {mustBeNumeric}=0 
end
app.StopYear = event.Value;
if app.StopYear<app.StartYear+1
    app.StartYear=max([app.StopYear-1 app.STARTKnob_2.Limits(1)]);
    app.STARTKnob_2.Value=app.StartYear;
    app.StopYear=app.StartYear+1;
    app.STOPKnob.Value=app.StopYear;
end
app.plotData();

[Mukesh]

Even after defining the upper and lower limits for xlim, why i am still getting the errror

[VBBV]

@Mukesh try with following change in these lines

app.StarYear.Value = event.Value
app.StopYear.Value = event.Value
xlim(app.UIAxes, [app.StartYear.Value app.StopYear.Value])

[Mukesh]

Thanks for all your help. I have figured out how it was initialised to same value. While setting the parameters for knob, the lower limit for both start & stop was set to 1850 by default. Thats why both had same value. Now i have created default function and sent the intital parameters accordingly and called it in startup function.

[VBBV]

@Mukesh if you dont want the default values of xlim to be used,

then inside the function plotData you need to put the xlim line with manual first which will override the default values.

function plotData(app)
xlim(app.UIAxes, 'manual') % put this line first 
%app.StarYear.Value = event.Value
%app.StopYear.Value = event.Value
xlim(app.UIAxes, [app.StartYear.Value app.StopYear.Value])

Answer 1

[Image Analyst]

You need to debug your program. See

Debugging in MATLAB | Doug's MATLAB Video Tutorials

After that, when you see an error that says the limits of the min and max values you're passing into xlim must be increasing values, you'll know how to check their values. What you need to do is set a breakpoint at xlim and hover over app to see what the values of StartYear and StopYear are. Or else just put them in the code right before xlim

app.StartYear
app.StopYear % No semicolons!
xlim(app.UIAxes, [app.StartYear, app.StopYear])

What are their values?

[Mukesh]

Thanks for suggestion.

[Image Analyst]

You said "Even after defining the upper and lower limits for xlim..." and I asked "what are their values?" You did not answer me. Why not? Did you try what I said?

[Mukesh]

Yes i tried your way. Both have same value (i.e 1850) but i don't know how both the variables are initialised to same value.

[Image Analyst]

How about if you just don't call xlim and let it automatically decide what the limits should be?

[Mukesh]

I am actually working on Appdesigner and these data need to be fixed so that i can plot the data

[Image Analyst]

So I assume that means you want the same start and stop values over multiple sets of data, instead of adjusting it on a vector-by-vector basis. But you're evidently setting them both to the same value.

Does your app have a startupFcn? If not, add one and set the app.Start and Stop to some default values. Or else use isempty() when you're trying to turn the knobs or plot data to make sure the start and stop values are not null.

Can you attach your GlobalTemp.mlapp so that I can fix it? Also a set of data if one is needed to run the program.

[Mukesh]

Thanks for all your help. But I have figured out how it was initialised to same value. While setting the parameters for knob, the lower limit for both start & stop was set to 1850 by default. Thats why both had same value. Now i have created default function and sent the intital parameters accordingly and called it in startup function. But your debug idea helped a lot.

Answer 2

[Walter Roberson]

You do not provide initial values for app.StartYear or app.StopYear, so they are initialized to [] (the empty vector)

Then when you test

if app.StartYear>app.StopYear-1

then app.StartYear = event.Value might have given a value to app.StartYear, but app.StopYear is still [] and testing (Value>[]) is false.

[Mukesh]

Considering above argument, error should be shown in function STARTKnob_2ValueChanging(app, event) or function STOPKnobValueChanging(app, event).

Why error is shown in xlim part(line 34)??

[Walter Roberson]

It is not an error to calculate with [] .

(It is typically an error to try to store [] into indexed locations. Not always though.)

With it not being an error to calculate with [], the error is not encounted until the call to

xlim(app.UIAxes, [app.StartYear app.StopYear])

with app.StopYear being [] the above call would collapse to

xlim(app.UIAxes, [app.StartYear []])

which would be

xlim(app.UIAxes, app.StartYear)

which would error because the input vector is only length 1.

[Mukesh]

Actually i have checked their value. I dont know how both variables are initialised to same value. So i understood why i was getting the error since it is not increasing numeric value input for xlim but now i am not gettting how how both variables are initialised to same value