!==================================

PROGRAM MORELOOPING

!==================================
! This program demonstrates how
! simple loops work
!==================================

  IMPLICIT NONE
  INTEGER :: i,j
  INTEGER, DIMENSION(10)  :: myvector !- vector of length 10
  INTEGER, DIMENSION(2,2) :: myarray !- 3x3 array

!-- simple loop

  do i=1,10
     myvector(i) = 1+i
     write(6,*) myvector(i)
  enddo   

!-- double loop (also called nested loop)
!-- IMPORTANT: in fortran the first index runs fastest
!-- in C/C++ it is the second one. 

  do i=1,2
     do j=1,2
        myarray(j,i)=i+i*j
        write(6,*)j,i,myarray(j,i)
     enddo
  enddo

!-- an example of using if statements (very artificial example)
!-- and comparing values using .AND. and .OR.

  do i=1,10
     do j=1,10
        if (i > 2 .OR. j>2) then
           if(i > 2 .AND. j>2) then
              write(6,*)'both i and j are too large', j,i
           else if(i>2 .AND. j <= 2) then
              write(6,*)'i is too large', i
           else if(i <= 2 .AND. j > 2) then
              write(6,*)'j is too large', j
           endif   
        else
           myarray(j,i)=i+i*j
        end if

     enddo
  enddo   

END PROGRAM MORELOOPING

!==================================