I need to make a nested loop with an arbitrary depth. Recursive loops seem the right way, but I don't know how to use the loop variables in side the loop. For example, once I specify the depth to 3, it should work like
count = 1
for i=1, Nmax-2
for j=i+1, Nmax-1
for k=j+1,Nmax
function(i,j,k,0,0,0,0....) // a function having Nmax arguments
count += 1
end
end
end
I want to make a subroutine which takes the depth of the loops as an argument.
UPDATE:
I implemented the scheme proposed by Zoltan. I wrote it in python for simplicity.
count = 0;
def f(CurrentDepth, ArgSoFar, MaxDepth, Nmax):
global count;
if CurrentDepth > MaxDepth:
count += 1;
print count, ArgSoFar;
else:
if CurrentDepth == 1:
for i in range(1, Nmax + 2 - MaxDepth):
NewArgs = ArgSoFar;
NewArgs[1-1] = i;
f(2, NewArgs, MaxDepth, Nmax);
else:
for i in range(ArgSoFar[CurrentDepth-1-1] + 1, Nmax + CurrentDepth - MaxDepth +1):
NewArgs = ArgSoFar;
NewArgs[CurrentDepth-1] = i;
f(CurrentDepth + 1, NewArgs, MaxDepth, Nmax);
f(1,[0,0,0,0,0],3,5)
and the results are
1 [1, 2, 3, 0, 0]
2 [1, 2, 4, 0, 0]
3 [1, 2, 5, 0, 0]
4 [1, 3, 4, 0, 0]
5 [1, 3, 5, 0, 0]
6 [1, 4, 5, 0, 0]
7 [2, 3, 4, 0, 0]
8 [2, 3, 5, 0, 0]
9 [2, 4, 5, 0, 0]
10 [3, 4, 5, 0, 0]
There may be a better way to do this, but so far this one works fine. It seems easy to do this in fortran. Thank you so much for your help!!!
you can define your function to have a List
argument, which is initially empty
void f(int num,List argumentsSoFar){
// call f() for num+1..Nmax
for(i = num+1 ; i < Nmax ; i++){
List newArgs=argumentsSoFar.clone();
newArgs.add(i);
f(i,newArgs);
}
if (num+1==Nmax){
// do the work with your argument list...i think you wanted to arrive here ;)
}
}
caveat: the stack should be able to handle Nmax
depth function calls