repeat a condition from the first iteration of for loop

I have an 'if' condition in a 'for' loop. But, the problem is when the condition is true and the code do sth then it continue the loop from the point that condition becomes true. Instead, I want that the code repeat the loop from the first iteration.

Answer 1

[Geoff Hayes]

Hamed - if your for loop is something like

 for k=1:n

then you can replace it with a while loop and allow the looping to continue from the first iteration whenever your condition is true

 k = 1;
 while k<=n

     if condition is true
         % do something

         % reset k to repeat loop from first iteration
         k = 1;
     else
         k = k + 1;
     end

 end

The only trick is making sure that you don't get stuck in this loop. When would the condition be false for all iterations that would finally cause the code to exit the loop?

[hamed]

I have sth like this: I want the interior for loop (k) will be repeated from the first if condition becomes true.

for i=2:n;
  %do sth
  for k=i-1:-1:1
     %do sth
     if condition is true
       %do sth
     end
  end 
end

[Geoff Hayes]

Ok. So can you not replace it with the while solution from above? There would be four differences: the initialization of k, the condition on the while loop, the re-initialization of k for when the condition is true, and the increment of k would have to be replaced with a decrement.

[hamed]

How can it be replaced with while?maybe like this?

for i=2:n;
    %do sth
     k=i-1
    while k>=1
       %do sth
       if condition is true
         %do sth
          k=i-1
       else
          k=k-1
       end
    end 
  end

[Geoff Hayes]

Does this not work?

 for i=2:m
    % do sth

    k=i-1;
    while k>=1
        % do sth
        if condition is true
            % do sth
            k = i - 1;  % to start the loop again
        else
            k = k - 1;  % to decrement
        end
    end
 end

Or am I misunderstanding your question? You stated that you want that the code repeat the loop from the first iteration and I want the interior for loop (k) will be repeated from the first if condition becomes true.

[hamed]

Ok, thank you very much. I guess this should work. I will test it tomorrow when back to uni cause i don't have matlab at home.