XL Fortran Enterprise Edition for AIX : User's Guide - IBM

-qrecur Option
Syntax
-qrecur | -qnorecur
RECUR | NORECUR
Not recommended. Specifies whether external subprograms may be called
recursively. For new programs, use the RECURSIVE keyword, which provides a
standard-conforming way of using recursive procedures. If you specify the -qrecur
option, the compiler must assume that any procedure could be recursive. Code
generation for recursive procedures may be less efficient. Using the RECURSIVE
keyword allows you to specify exactly which procedures are recursive.
Examples
! The following RECUR recursive function:
@process recur
function factorial (n)
integer factorial
if (n .eq. 0) then
factorial = 1
else
factorial = n * factorial (n-1)
end if
end function factorial
! can be rewritten to use F90/F95 RECURSIVE/RESULT features:
recursive function factorial (n) result (res)
integer res
if (n .eq. 0) then
res = 1
else
res = n * factorial (n-1)
end if
end function factorial
Restrictions
If you use the xlf, xlf_r, xlf_r7, f77, or fort77 command to compile programs that
contain recursive calls, specify -qnosave to make the default storage class
automatic.
224 XL Fortran Enterprise Edition for AIX : User’s Guide