Re: Numerical Integration

[Jaroslav Hajek]

On Sun, Dec 7, 2008 at 1:21 PM, Søren Hauberg <address@hidden> wrote:
> søn, 07 12 2008 kl. 12:38 +0100, skrev Jaroslav Hajek:
>> With more modern Fortran compilers, recursion is no problem (just
>> declaring the procedure RECURSIVE). A lot of problems with the Fortran
>> sources could go away if we resigned on compatibility with the ancient
>> f2c and g77.
>
> Could we just check if it is possible to make a procedure RECURSIVE
> during compilation?

That's a good suggestion. A problem with this is that there is no
standard preprocessor for Fortran, so we would need to preprocess the
sources externally from a Makefile, using sed or some other tool. But
in principle, it's doable.

> If it is possible, we could let 'quad' work
> recursively, and if not we could fall back to the current situation. Or
> perhaps it would be a bad thing if some code worked on some platforms
> but not on others?
>
>> The principal obstacle to doing so is that for building with MSVC on
>> Windows, no suitable Fortran 90 compiler is freely available. It
>> doesn't seem acceptable to require users that want to build themselves
>> with MSVC to also purchase Intel Visual Fortran or similar product (we
>> could get money together to buy our regular Windows builders a
>> license, so that binaries would still be available).
>
> Perhaps Intel could be persuaded to donate a few licenses to their
> compilers? What about mingw -- does that come with a fortran compiler?
>

I bet it could, especially if that meant that people wanting to build
Octave on Windows using Visual Studio would have increased interest in
purchasing Visual Fortran.
However, those people would find a new obstacle in the process with no
free alternative, and that could mean a loss of users for Octave.

As for mingw, I suggested that to Michael Goffioul some time ago, but
he explained that the problem is that the runtime libraries are
incompatible in some way - I don't remember the details.

I'm not sure how many people actually do build Octave with MSVC - my
impression is that Windows users are far more accustomed to
downloading binaries.
I think you can still get MSVC++ free for personal use. The only
MSVC-compatible windows Fortran compiler I know that can also be
obtained for free is Salford Fortran 95:
<http://www.silverfrost.com/32/ftn95/ftn95_personal_edition.asp>
This would actually be an excellent choice (provided that you can live
with the start-up banner displaying in the personal edition, and I'm
not even sure it pops up from a shared library), but I think that the
license is more restrictive than those of Visual Studiou Express,
perhaps disallowing selling the binaries. But I may be wrong. If
anyone would find the time to investigate this (perhaps ask Salford
directly), that would be great.

> Søren
>
>



-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz