How to I change the time step in the following loop, so the new time is for the next line of code beign read?

So I have this data that is a three column vector, which has 30 rows. The data is in the columns: volts, counts, time. The time column all says 500ms for all of the rows. But for the second row I would like the time to be adjusted to 1000ms, then by 1500ms and so on and so forth for all of the other lines of data. How do I do this for inside the loop? Also how do I plot this accordingly, I am using a GUI, through using guide.

 %Variables
p = 1000;
g = 9.81;
vs = 5;

 while fgetl(handles.fid)~= -1
    line = fgetl(handles.fid);
    new_line = sscanf(line, '%f V, %i counts, %i ms');
    t = new_line(3)/1000;

    % Q = flowrate (L/s)
    % h = head(m)
    % P = pressure
    % p = density of water

    P = ((new_line(1)/vs) - 0.04)/0.0018;

    % Finding head
    h = (P/1000)/(p*g);

    Q = new_line(2)/((t/1000)*330);

    % Finding hydraulic power
    H =(Q*p*g*h)/1000;

    %%%%%%%%%%%%%%%%%%%%%Plotting %%%%%%%%%%%%%%%%%%%%%%%%%
    hold all
    handles.plot = plot(handles.axes1, t, P, 'o-');
    drawnow
    handles.plot2 = plot(handles.axes2, Q, t, 'o-');
    drawnow
    handles.plot3 = plot(handles.axes3, h, Q, 'o-');
    drawnow
    handles.plot4 = plot(handles.axes4, H, Q, 'o-');
    drawnow

    handles.data.pressure = P;
    handles.data.time = t;
    handles.data.hpower = H;
    handles.data.flowrate = Q;
    handles.data.head = h;

    %Update handles
    guidata(hObject,handles);
end

 %save changes to the handle
 guidata(hObject,handles);

[jonas]

Do you mean that the time vector specifies the time step, and what you want is the total time elapsed?

If so, then you can use

t_tot=cumsum(t)

Answer 1

[Sammit Jain]

To handle this more intuitively, you can initialize a counter outside the loop (say k=0).

Inside your loop you can then make the following change to get the total time elapsed:

t = new_line(3)*k/1000;

This should initialize every iteration with t as the time elapsed till then.