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From: sterner@strdev.jhuapl.edu (Ray Sterner)
Subject: Re: Q: Who knows IDL?
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Date: Wed, 17 May 1995 18:18:24 GMT
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Xref: glinda.oz.cs.cmu.edu sci.image.processing:14680 comp.lang.idl-pvwave:4531

grunes@news.nrl.navy.mil (Mitchell R Grunes) writes:

  . . .

>IDL and its very similar sister PV-WAVE are discussed in 
>newsgroup comp.lang.idl-pvwave.  You might look at the FAQ:
>  ftp://rtfm.mit.edu/pub/usenet/comp.lang.idl-pvwave

  The latest IDL FAQ as a web page is at:

     ftp://fermi.jhuapl.edu/www/s1r/idl/idl_faq/idl_faq.html

  Text and compressed versions (HTML and text) are in the same directory.

>There are at least six minor deficiencies of IDL and PV-WAVE:
>(1) If you can't recast a problem into array notation, loops are quite
>    slow.  These are interpreters.  They will never replace Fortran
>    or C.

  Loops are no problem if you can do enough processing each time
  through a loop.  Before starting a major project some time ago
  we were trying to decide what language to use, C or IDL.  Some C
  software existed to do a needed job and I was challenged to do the
  same job in IDL.  I wanted to use IDL and was told that if the
  processing time was within a factor of 2 or so then IDL could be
  used.  The C code was by a good C programmer.  Unexpectedly my
  IDL software was about twice as fast as the C.  Some excuse was
  offered (can't remember exactly what it was) but I pointed out that
  the excuse would not have been mentioned if the C code had been
  faster.  Development time is much faster with IDL.  I have done
  both FORTRAN and C in the past but have no real need for them
  any longer (I know some applications do require them).

  Ray Sterner                     sterner@tesla.jhuapl.edu 
  The Johns Hopkins University    North latitude 39.16 degrees.
  Applied Physics Laboratory      West longitude 76.90 degrees.
  Laurel, MD 20723-6099
  WWW Home page:  ftp://fermi.jhuapl.edu/www/s1r/people/res/res.html
