If you have R2014b or later, I suggest you create some animatedLine with your desired maximum length, and addpoint() the data as it comes in.
If you are not trying to limit the length of the lines then I would suggest:
gdata = []; %initialize
for index = 1 : inf
[gx, gy, gz] = readAcc(accelerometer);
gdata = [gdata; gx, gy, gz];
plot(1:index, gdata);
drawnow();
end
Except that more efficient would be:
gdata = []; %initialize
hx = line(nan, nan, 'color', 'r'); %do not use [] to initialize them
hy = line(nan, nan, 'color', 'g');
hz = line(nan, nan, 'color', 'b');
for index = 1 : inf
[gx, gy, gz] = readAcc(accelerometer);
gdata = [gdata; index, gx, gy, gz];
set(hx, 'XData', gdata(:,1), 'YData', gdata(:,2));
set(hy, 'XData', gdata(:,1), 'YData', gdata(:,3));
set(hz, 'XData', gdata(:,1), 'YData', gdata(:,4));
drawnow();
end
