Re: isnan in fortran

[Michael Goffioul]

On Wed, Apr 11, 2012 at 12:24 PM, John W. Eaton <address@hidden> wrote:
> On 11-Apr-2012, John W. Eaton wrote:
>
> | On 11-Apr-2012, c. wrote:
> |
> | |
> | | On 10 Apr 2012, at 19:00, address@hidden wrote:
> | |
> | | > I think it would be better to rename the files that need this
> | | > treatment to FILE.in.f and then use sed to do the transformation to
> | | > generate FILE.f in the build tree.
> | | >
> | | > jwe
> | |
> | | I am preparing a patch to do that.
> |
> | After giving it some more thought, it might be better in this specific
> | case to have a configure test that checks whether isnan is available
> | in Fortran and if not, adds misc/isnan.f to the list of functions to
> | compile.  The misc/isnan.f function could be
> |
> |       logical function isnan (x)
> |       double precision x
> |       if (x != x)
> |         isnan = .false.
> |       else
> |         isnan = .true.
> |       endif
> |       return
> |       end
>
> Uh, except that I have the test and some syntax wrong.  How about
>
>       logical function isnan (x)
>       double precision x
>       isnan = x .ne. x
>       return
>       end

Sounds like a good plan. Would we also need a single precision version?

Michael.