Hi, How to write the code with random number of iterations?

Hi, there are two parameters, n and d. We repeat n times experiments. In each experiment, there are d possibilities.

So there are d^n combinations.

So I have to write like this:

for i=1:d
   for j=1:d
      ..... until the nth for

and then 
  end
end ...

But I do not know the values of n and d.

[Walter Roberson]

possibly ndgrid().

[Vivian]

Thank you Walter. This is very useful.

Answer 1

[Jan]

You can avoid the nested FOR loops by using a vector as counter and one WHILE loop:

n     = 4;
d     = 5;
index = ones(1, n);
doRun = true;
while doRun
  disp(index);  % insert your operations here

    % Update the index:
    doRun = false;
    for k = n:-1:1
      index(k) = index(k) + 1;
      if index(k) <= d
         doRun = true;
         break;      % Leave "for k" loop
      end
      index(k) = 1;  % Reset k.th counter
    end
  end

[Azzi Abdelmalek]

Amazing approach! +1

Answer 2

[Azzi Abdelmalek]

You can do it using eval function

d=10
n=5
out=0
s1=sprintf('for k%d=1:%d,',[1:n;repmat(d,1,n)]); % The n first for loop
s2='out=out+1,' % your calculations
s3=repmat(',end',1,n) % the n end
s=[s1 s2 s3]
eval(s) % to execute your for loop

Maybe there is another alternative: a function that calls itself n time

[Vivian]

Thank you Azzi. This does help me.

[Jan]

EVAL is always a bad solution. Injecting variables dynamically in a workspace slows down the JIT massively.