I think, I might have a problem with the 'hold' part and I get the 'error while evaluating button privatebuttonpushedfcn'

i have this in the code view for the app:

% Button pushed function: PlotButton

function PlotButtonPushed(app, event)

fnam = uigetfile ('*.dat','Escolha o ficheiro');

fid = fopen(fnam);

ecg = fscanf(fid,'%f');

fs = 200; %sampling rate

sze = length(ecg);

necg = ecg/max(ecg); % normalize the maximum value to unity

time = (1:sze)/fs;

[mins, maxs] = picos (necg);

figure;

plot(app.UIAxes, time, necg, 'b');

hold on;

plot (app.UIAxes, time(maxs), necg(maxs), 'red*');

plot (app.UIAxes, time(mins), necg(mins), 'ko'); hold off;

axis tight;

ylabel(app.UIAxes, 'ECG');

xlabel(app.UIAxes, 'Time in seconds');

But when i press run, and then the plot button, choose a file, all i get in the Axes window is the black dots that mark valleys in the signal plus, it opens a different window with a blank figure. I need to show the signal, the valleys marked with a dot and the peaks marked with a star in the app.UIAxes and i dont want to open the other window with the blank figure.

Here is the code for "picos" function:

function [mins, maxs] = picos (sinal)

mins = [];

maxs = [];

t = 1:length (sinal);

for i = 2:length(sinal)-1

if sinal(i-1) > sinal(i) && sinal(i) < sinal(i+1)

mins = [mins i]; %faz acrescentar o valor de i ao array mins

end

if sinal(i-1) < sinal(i) && sinal(i) > sinal(i+1)

maxs = [maxs i]; %faz acrescentar o valor de i ao array maxs

end

end

% plot (t, sinal, 'm-'); hold on;

% plot (t(maxs), sinal(maxs), 'b*');

% plot (t(mins), sinal(mins), 'go'); hold off;

% title ('Deteção picos'); xlabel ('Tempo (s)'); ylabel ('Sinal (t)');

end

Thank you!

Answer 1

[Voss]

You need to tell hold() and axis() to operate on your app's axes:

...
hold(app.UIAxes,'on')
...
hold(app.UIAxes,'off')
...
axis(app.UIAxes,'tight')
...

And remove the "figure;" call if you don't want a blank figure to pop up.

[HELENA]

oh ok, thank you!

[Voss]

You're welcome!

Answer 2

[Steven Lord]

Don't call figure if you don't want to create a new figure.

[HELENA]

thank you!