fortran77 - Function pointers in fortran -

is possible have function pointers in fortran? right have code lines this:

subroutine flag(iflag,a,b)  integer n, a, b, ii, iflag  ii = 1, n      if (iflag.eq.0) a+b      else a-b   end      return end 

the variable "n" has huge value , run code, feel wasting lot of time "if" command. possible write function pointer (i not sure mean that), such @ code this:

subroutine flag(iflag,a,b)  *depending on iflag subroutine flag automatically  precompiled call either flag_plus or flag_minus*       return end  subroutine flag_plus(a,b)  integer n, a, b, ii  ii = 1, n      a+b end      return end  subroutine flag_minus(a,b)  integer n, a, b, ii  ii = 1, n      a-b   end      return end 

if possible can save lot of time avoiding "if" loop. remotely possible?

in fortran 77 can have limited variant of function pointers, namely can pass name of procedure argument procedure (a function pointer, essentially). cannot have variable contains address of procedure , "call" variable, though.

as of fortran 2003, procedure pointer variables part of language.

that being said, think example problem solved easier like

 if (iflag == 0)  ! why iflag not of type logical?   ii = 1, n     + b   end else   ii = 1, n     - b   end end if 

make sure profile see whether has effect, well. modern cpu's have pretty branch predictors, , branch test doesn't change during entire loop pretty best case scenario (rule of thumb: predicted branches close free). heck, compiler might able above kind of optimization..