embedded matlab function error message

1 view (last 30 days)
mado
mado on 8 Feb 2013
i have this error message
"Output argument 'dvref' is not assigned on some execution paths."
when executing this code
function dvref =IC(V,I)
persistent Vref Vold Iold c;
if isempty(Vold)
Vold=0; %initialized only once in the beginning
end
if isempty(Iold)
Iold=0; %initialized only once in the beginning
end
if isempty(c)
c = .1; %initialized only once in the beginning
end
if isempty(Vref)
Vref=.5; %initialized only once in the beginning
end
dI=I-Iold;
dV=V-Vold;
if V==Vold
if I~=Iold
elseif I>Iold
dvref=Vref-c
else dvref=Vref+c
end
elseif dI/dV~=-I/V
if dI/dV > -I/V
dvref=Vref-c
else
dvref=Vref+c
end
end
Iold=I
Vold=V

Answers (4)

Walter Roberson
Walter Roberson on 8 Feb 2013
In your "if I~=Iold" case you do not assign anything to dvref .
  1 Comment
mado
mado on 8 Feb 2013
actually this is not the problem i tried it but in a vain , error is still there.

Sign in to comment.


mado
mado on 8 Feb 2013
the answer is that dvref should be outside the if condition but in my flowchart it'snot outside the if condition ,so i don't know how to implement it any one help

Azzi Abdelmalek
Azzi Abdelmalek on 8 Feb 2013
Are you sur one of these two expression
  • if V==Vold
  • elseif dI/dV~=-I/V
is true for each step?
  14 Comments
Azzi Abdelmalek
Azzi Abdelmalek on 8 Feb 2013
Edited: Azzi Abdelmalek on 8 Feb 2013
You can use a unit delay block to get the previous value of dvref. Name it dvref_old, then in your code instead of "Doing nothing" you will do:
dvref=dvref_old

Sign in to comment.


mado
mado on 8 Feb 2013
if I-Iold=0 if yes return if no check the next step i don't know "return" here is right or not, so i reversed it i checked the inequality and so on
  2 Comments
mado
mado on 9 Feb 2013
ok , how to do this using simulink i think it will be easier

Sign in to comment.

Categories

Find more on Loops and Conditional Statements in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by