how to go back in previous iteration

i was trying to run an iterative process in while loop.it is conditional based iteration, if the condition is satisfied in current iteration then continue to next iteration else go to previous iteration as long as condition is not satisfied.

i have considered iter=iter-1 for previous itertion in if loop and then used break command to terminate while loop . will it go back in previous iteration with this condition. suggestion will be appreciated.

thanks in advance...

Answer 1

[Walter Roberson]

The only way to go back to a previous iteration is to use a while loop and make the loop counter the appropriate previous value and then "continue".

It is much more common to want to stay on the current iteration until a condition is satisfied. For that, you can use a while loop within a for loop

   for K = 1 : number_of_iterations
     while true
       do a calculation
       if condition is satisfied
         break
       end    %end if
     end      %end while
   end        %end for

[vipin pandey]

but in my problem the current output is dependent upon the previous output. so if current output condition is not satisfied it need to go back in previous output and made suitable change so current condition is satisfied

[Walter Roberson]

Then you can use a while loop and set the loop control variable to the previous value and "continue". For example,

i = 1;
while i < 10
  disp(i);
  if i < rand()*10
    i = max(1, i - 1);
    continue;
  end
  i = i + 1;
end

[vipin pandey]

i have used for loop for 24 interval then while loop in nested and if command for conditional violation is used e.g. if 12th interval condition is not satisfied then it should go 11th interval but for loop is used for interval so how will for loop go back in 11th interval if 12th interval loop is run. for loop is used for interval so it can not be eliminated. example as given below

for i=1:24
count=1;
maxcount=100;
while index==0
if condition satisfied 
index=1
break
end
count=count+1;
if count>maxcount
i=i-1;
break
end
end
end

[Walter Roberson]

If someone has imposed a constraint on you that a for loop must be used, then you will need to rethink your implementation.

Otherwise just convert the for loop to a while loop

i = 1;
while i <= 24
  ....
end

and remember to increment i when you are ready to move forward.

[vipin pandey]

 i got the answer thank you for your valuable suggestion