How to skip a few iterations in a do loop in Fortran

Question

For example, I want to loop from 1 to 500 at an increment of 2. However, for every 8 loops I want to skip the next 18 loops (make the do-variable increase by 18). How do I d

Answer 1

consider a nested loop for this example, something like

  do k=0,15
    do j=0,7
      i=34*k+2*j  ! 34 == 18+2*8
        ....
   end do
  end do

(probably i don't have the arithmetic right but you see the idea)

Answer 2

It is forbidden to modify the loop index. You can solve your problem in several ways. For instance, here is a solution without explicit loop index :

i = -1
do
    i=i+2
    if(i > 5000) exit
    if (i == 15) i=i+18
    ...
enddo