Fortran 77 did not explicitly allow recursive functions and subroutines, although there were several ways around this eg Fortran Examples. From Fortran 90 onwards, recursive functions and subroutines could be declared and used freely.
A well known recursion benchmark:
program ackermann integer :: ack write(*,*) ack(3, 12) end program ackermann recursive function ack(m, n) result(a) integer, intent(in) :: m,n integer :: a if (m == 0) then a=n+1 else if (n == 0) then a=ack(m-1,1) else a=ack(m-1, ack(m, n-1)) end if end function ack
|gfortran 4.4.3||Fortran||2.97 s|
|gfortran 4.6.0||Fortran||2.91 s|
|g95 0.93||Fortran||6.19 s|
(Note that the Fortran version can perform at the same speed as the C implementation if F2003 pass-by-value is used.)