plotting from a loop

Question

for t=0:0.1:10;
VS=3*exp(-t/3).*sin(t*pi);

    if VS>0
        VL(t+1)=VS;
    else 
        VL(t+1)=0;

    end
end


plot(0:100,VL);
xlabel('Time(s)')
ylabel('Across Voltage(V)')
title('Across Voltage Vs Time')

how to plot this figure based on VL (based on the relationship with VS whose expression shows above) versus t(from 0 to 10, increment 0.01)?

always got the error from matlab "Subscript indices must either be real positive integers or logicals."

Thanks.

see [here](http://stackoverflow.com/questions/15262163/plotting-a-result-from-a-loop-in-matlab/15262205#15262205) for answer. — Autonomous, Mar 07 '13 at 06:38
Also see [this question](http://stackoverflow.com/questions/20054047/subscript-indices-must-either-be-real-positive-integers-or-logicals-generic-sol) for [the generic solution to this problem](http://stackoverflow.com/a/20054048/983722). — Dennis Jaheruddin, Nov 27 '13 at 16:09

score 1 · Accepted Answer · answered Mar 07 '13 at 06:35

There is a problem in your script. Note that t is defined in 0.1 intervals. Therefore, it is a real variable and can't be used as a subscript indice.

One way to solve that is

1) write cont=0; before the loop for.

2) write cont=cont+1 in the beginning of the loop

3) replace VL(t+1) by VL(cont)in both places inside the loop

plotting from a loop

1 Answers1