In fortran, AFAIK, be care of using pointer, this make your code more like
C. The side effect is the more times you use pointer, the less chance your
compiler can optimize your code (Alias Opti.). This is one of why, in
numerical computation, fortran can be generally faster than C without
manual optimization.
Best regards
qxb
On 11/9/05, Ross Walker <ross.rosswalker.co.uk> wrote:
> I am pretty reluctant to require a Fortran 2003-compliant compiler for
> Amber 9. Is there any easy way to not have to use
> allocatable arrays inside
> user-defined types?
I think this can be done with pointers instead of 'traditional'
allocatable
arrays. E.g.
type chang_miller_type
_REAL_, allocatable :: q( :)
_REAL_, allocatable :: d( :)
_REAL_, allocatable :: k(:,:)
.
.
.
end type
becomes:
type chang_miller_type
_REAL_, pointer :: q( :)
_REAL_, pointer :: d( :)
_REAL_, pointer :: k(:,:)
.
.
.
end type
This 'should' be completely compatible and, assuming they don't use:
if(allocated(blah))
then no other changes are necessary. If they do use the allocated() call
then you need to go through and set every pointer initially to null and
then
instead of if (allocated()) just check if the pointer is still null.
Pointers are also much more versatile since you can use the pointer
assignment command to flip arrays rather than doing a copy. E.g.
Instead of
do
! fill p with data based on pold and new stuff...
...
! copy p into pold to use as the starting point for next time...
pold(1:natom) = p(1:natom)
end do
Or similar pseudo code... You can do
_REAL_, dimension(:), pointer :: temp_ptr
do
! fill p with data based on pold and new stuff...
...
! copy p into pold to use as the starting point for next time...
!Store the pointer to p
temp_ptr => p
p => pold
pold => temp_ptr
end do
This allows you to flip flop back and forth between the two arrays without
actually doing an array copy.
Any volunteers for going through all the evb code???
All the best
Ross
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|\oss Walker
| Department of Molecular Biology TPC15 |
| The Scripps Research Institute |
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--
... there have been two really clean,
consistent models of programming so far:
the C model and the Lisp model.
These two seem points of high ground,
with swampy lowlands between them.
--Paul Graham
Received on Wed Apr 05 2006 - 23:49:51 PDT
