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Re: passing Indeterminate and Infinity to C via MathLink

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121618] Re: passing Indeterminate and Infinity to C via MathLink
  • From: Roman <rschmied at gmail.com>
  • Date: Thu, 22 Sep 2011 07:26:50 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <j4vamb$dah$1@smc.vnet.net> <j59os9$pc$1@smc.vnet.net> <j5cb36$cs6$1@smc.vnet.net>

On Sep 21, 11:34 am, David Bailey <d... at removedbailey.co.uk> wrote:
> On 20/09/2011 11:11, Roman wrote:
>
> > Dear John,
> > thanks a lot for your detailed explanations. I believe that your
> > suggestion of using "magic" floats for representing Indeterminate and
> > Infinity is the most viable possibility; in this way I can send packed
> > arrays to C without a hitch.
> > The inefficiencies that you mention in the MathLink protocol, even
> > using packed arrays, are quite noticeable though. Much experimentation
> > and comparison to the use of Compile[] is required to find the fastest
> > way of getting things done.
> > Best regards,
> > Roman
>
> One alternative to designating a magic float (which then has to be
> searched for in the external program, and which could be generated by an
> unfortunate calculation) is to replace the NaN values with 0.0, and also
> send a small (packed integer) index array locating the NaN's. If there
> are no Nan's, the list would be empty.
>
> David Baileyhttp://www.dbaileyconsultancy.co.uk

Brilliant! Thanks David.




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