plotting results of an while loop

Hi I have to plot the speed of a Basejumper in dependence of the time. For this I'm using a while loop with the plot command underneath. That's my code:

while s>0%
  a=g+k/m*v.^2;
  deltav=a*deltat;
      v=v+deltav
      deltas=v*deltat;
      s=s+deltas;
      t=t+deltat;
end
plot(t,v)
hold on

sprintf('Der Flug dauerte %5.3f Sekunden',t)
sprintf('Die Geschwindigkeit beim Aufschlag betrug %5.3f m/s',v)

Unfortunately Matlab shows only one point in the diagram not the whole graph. Does anybody knows what I did wrong?

Thanks Fabian

Answer 1

[Sean de Wolski]

You overwrite t,v on each iteration of the for-loop. Instead you need to either plot them then or store them to plot later.

count = 0;
while ...
  count = count+1;
  v(count) = v(count-1)+deltav;
end

or plot as you're going;

hold on
while ...
  %stuff
  plot(t,v)
end

[BHAGYASHREE WAGHULE]

Hello Sean, I tried your first suggestion of using count, but it gives an error saying the subscript indices must either be real positive integers or logicals.

[VBBV]

ok, i think it will give error, because Matlab uses 1 based indexing,

while ...
  count = count+1;
  v(count+1) = v(count)+deltav;  % use this instead, (count-1) = 0 ; Matlab 
end

e.g.

S = 1:10;
S(0)

Array indices must be positive integers or logical values.

Answer 2

[Fabian Höfler]

Yeah! It's running thanks a lot.