At 10:00 14-11-2000 -0800, Richard Maine wrote:

 [ snip ...]

>  I'll probably mess it up off the top of my head, in which
> case I'm sure corrections will be given, but something like
>
>  real(working_kind) :: x
>  integer, parameter :: higher_kind = selected_real_kind(precision(x)+1)
>
>You might be able to get fancier and ask for a higher precision if
>available, settling for the same kind if it's already the highest,
>but I don't think I'll try the trick of writing that as an
>initialization expression.  (Probably doable, but also probably
>ugly.  I might be tempted to just make it a system-dependent
>parameter and hand-set it in a system-dependent module).
>
>For my part, I never use double precision declarations in f90 code.
>If I really wanted double precision, I'd still use the kind syntax
>and use the rd_kind parameter from my precision module.  This
>code lifted right out of the module I normally use - though I far
>more commonly use some of the other parameters from the module.
>(Most on the list will probably recognize the derivations of
>several of my parameter names).
>
>!-- 4 Mar 92, Richard Maine: Version 1.0.
>
>module precision
>
>  !-- Kind constants for system-independent precision specification.
>  !-- 4 Mar 92, Richard Maine.
>
>  implicit none
>  public
>
>  !-- System default kinds.
>  integer, parameter :: i_kind = kind(0)      !-- default integer
>  integer, parameter :: rs_kind = kind(0.)    !-- real single precision
>  integer, parameter :: rd_kind = kind(0.d0)  !-- real double precision
>
>  !-- Kinds for specified real precisions.
>  integer, parameter :: r4_kind = selected_real_kind(6,30)   !-- 6 digits
>  integer, parameter :: r8_kind = selected_real_kind(12,30)  !-- 12 digits
>
>  !-- Kinds for specified integer ranges.
>  integer, parameter :: i1_kind = selected_int_kind(2)  !-- 99 max
>  integer, parameter :: i2_kind = selected_int_kind(4)  !-- 9,999 max
>  integer, parameter :: i4_kind = selected_int_kind(9)  !-- 999,999,999 max
>
>  !-- Kind for working real precision.
>  integer, parameter :: r_kind = r8_kind

If you are interested in the highest available precision or range
you can find it using the following module.

!-->
!    [JvO]    2000-08-13         Prec-mod.f90
!-->
!  Define highest integer range and real precision kinds.
!-->
  module precision_M
    implicit NONE
    integer, parameter :: byte = selected_int_kind(1)
    integer, parameter :: word = selected_int_kind(range(1_byte)+1)
    integer, parameter :: long = selected_int_kind(range(1_word)+1)
    integer, parameter :: extd = selected_int_kind(range(1_long)+1)
    integer, parameter :: mpi  = max(byte,word,long,extd) ! Highest
!                         ^^^
    integer, parameter :: sp = kind(1.0e0)
    integer, parameter :: dp = kind(1.0d0)
    integer, parameter :: ep =                   &
      &  selected_real_kind(precision(1.0_dp)+1)
    integer, private, parameter :: c = (sign(1, ep) +1) / 2
    integer, parameter :: mpr = (1-c) * dp + c * ep  !  Highest available
!                         ^^^   Another way to do the same.
    character(len=*), parameter :: fmt_I = "(A, T11, I21)"
    character(len=*), parameter :: fmt_R = "(A, T11, G28.18E4)"
  end module precision_M



--

Meilleures Salutations,
Kindest Regards,
/---
Jan van Oosterwijk
Computing Centre
Delft University of Technology
Postbus    354
2600 AJ  Delft
Netherlands / Pays-Bas
mailto:[log in to unmask]
Phone: +31 15 27 85017
Fax:   +31 15 27 83787




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