INTEGER JEFF(3)
DATA JEFF/4HMR. ,4HFORT,3HRAN/
If you can understand that, you should probably pretend you can't :-)
-Paul [who has actually used Computed GO TO and Arithmetic IF]
On Fri, Feb 20, 2015 at 11:28 AM, Larry Baker <ba...@usgs.gov> wrote:
> Excellent, Mr. Fortran. Thank you.
>
> By the way, I meant to write Branch ON Low Bit Set/Clear.
>
> Larry Baker
> US Geological Survey
> 650-329-5608
> ba...@usgs.gov
>
>
>
> On 20 Feb 2015, at 11:22 AM, Jeff Squyres (jsquyres) wrote:
>
> On Feb 20, 2015, at 2:12 PM, Larry Baker <ba...@usgs.gov> wrote:
>
>
> Beware, this has/may not always be the case. This is due to C's
> historical confusion/misuse of integers as boolean data types. On VAX
> hardware, the low bit was the only significant part of a Fortran LOGICAL
> data type, owing to the architectural support (Branch of Low Bit Set/Clear)
> for the low bit in a status word meaning success/failure. I doubt anyone
> uses VAXes and MPI, so this is not likely to cause users problems.
>
>
> Note that this comment was referring to two things:
>
> 1. 0/1 array index issues
> 2. .true./.false. issues
>
> We actually check for the value of .true. in configure, and use that
> everywhere. I believe this particular portion of the code simply looks for
> .false.==(C int)0, and .true. is anything else. That was deemed good
> enough because this portion of the code is simply *checking* for
> true/false. Where we *assign* true/false in the Fortran boolean sense, we
> use the value determined by configure.
>
> --
> Jeff Squyres
> jsquy...@cisco.com
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
>
> _______________________________________________
> devel mailing list
> de...@open-mpi.org
> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel
> Link to this post:
> http://www.open-mpi.org/community/lists/devel/2015/02/17012.php
>
>
>
> _______________________________________________
> devel mailing list
> de...@open-mpi.org
> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel
> Link to this post:
> http://www.open-mpi.org/community/lists/devel/2015/02/17013.php
>
--
Paul H. Hargrove phhargr...@lbl.gov
Computer Languages & Systems Software (CLaSS) Group
Computer Science Department Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
