[comp.lang.idl-pvwave] Difference between IDL and PV-WAVE Explained

gotwols@warper.jhuapl.edu (Bruce Gotwols) (07/15/90)

Several people have posted questions asking about the difference between IDL
and PV-WAVE.  IDL (Interactive Data Language) is a product of RSI (I forget the
meaning, Research ...) and is the creation of David Stern.  IDL goes back to
PDP-11 days, but I don't know the exact chronology.  I have used it since 
about 1984 on a VAX.  PV-Wave is a product that builds on top of IDL, providing
menus and other useful utilities.  There is something very strange about the 
fact that most users of PV-Wave are unaware that they are using a product which 
might be classified as a shell that sits on top of IDL.  Don't attack me...
it does more than just provide menus, but basically it is NOT a language since,
it relies on IDL to provide a language you can program in.  So the user who 
recently said that PV Wave is far superior to IDL must have liked the menus,
but as far as programming is concerned he is wrong since the two are identical
as a programming language.  For my own part, I attended a demo of the PVWAVE
product and decided not to purchase it.  I almost never find a product that
does the sort of specialized things I do, so the nice PVWAVE menus were not
worth purchasing since I wouldn't use them anyway.  For more routine stuff you 
might easily come to the opposite conclusion.  I must admit that I was not 
pleased that neither the PVWAVE salesman nor the PVWAVE manuals (at least at 
that time) admitted that their product was built on top of the IDL language.
I guess that's one nice benefit that will come out of this new combined 
newsgroup, a bit of information exchange between users of both products.

So it is possible for IDL and PV-Wave users to exchange programs as long as the
programs don't rely on specific features that are only present in the add-on
PV-Wave product.  A shared library of Astronomy oriented IDL source code 
allready exists at the Goddard Space Flight center, but I believe it has
restricted access.  I have contacted the people in charge and hope they will
soon make some or all of their holdings available for people on the Internet.
About 500 routines are also available from the Johns Hopkins Applied Physics 
Laboratory, most written by Ray Sterner, and an infinitesmal number by myself.
We hope to contribute the more general ones to an IDL remote ftp site when
one is finally set up.  Most of these routines were initially written in IDL
version 1, which runs only on a VAX.  Currently Ray is converting many
of them to IDL version 2, which is compatible with both VAX under VMS, and
SUN under UNIX.  
--
--
Bruce L. Gotwols
Johns Hopkins University, Applied Physics Lab., Laurel MD 20723
Internet:  gotwols@warper.jhuapl.edu   (128.244.176.48)

lumsdon@dtoa1.dt.navy.mil (Lumsdon) (07/16/90)

Following Bruce's excellent posting, I'd like to point out a couple
of things.

The pricing for IDL and PV-WAVE was similar, when I looked about 8 months
ago. Both companies are in the Denver/Boulder CO area. Precision Visuals
licensed the technology, source, and manuals from RSI.

I believe that the newer versions of IDL and PV-WAVE work with X-windows,
and use names rather than numbers for parameters to some commands.

IDL supports more output devices, Grinnell image processor and Gould
image processor, for example.

The source for creating menus (using the PV-WAVE facility) is included.
It might be possible to write equivalent commands for IDL without a
lot of trouble.

For version of PV-WAVE that we have, one of the three manuals is identical
to one of the IDL manuals. The user library is identical to that supplied
with IDL.

So, the two products are quite similar in ancestry, capability, and
price.

--------------------------  Esther Lumsdon  --------------------------------
lumsdon@dtoa1.dt.navy.mil  lumsdon@dtrc.dt.navy.mil
lumsdon%dtrc.navy.mil@uunet.uu.net
"Wherever you go, there you are" -Buckaroo Bonzai

steve@bat.lle.rochester.edu (Steve Swales) (07/17/90)

In article <5944@aplcen.apl.jhu.edu> gotwols@warper.jhuapl.edu (Bruce Gotwols) writes:
>There is something very strange about the fact that most users of PV-Wave
>are unaware that they are using a product which 
>might be classified as a shell that sits on top of IDL.
and:
>I must admit that I was not 
>pleased that neither the PVWAVE salesman nor the PVWAVE manuals (at least at 
>that time) admitted that their product was built on top of the IDL language.

I have heard (from an informed source) that in fact it was stipulated
by RSI in their license to PV that the relationship NOT be revealed.
This is indeed strange, IMHO, like C++ trying to deny relationship to
C (or vice versa). The idea, as I was told, is that RSI does not want
to be bothered by PV-WAVE customers since they already have there own
base of IDL people. While I can understand this desire, I don't think
that this stipulation was the way to go, and in fact, the whole thing
seems kind of paranoid, if true. Anyone know the true facts?

>I guess that's one nice benefit that will come out of this new combined 
>newsgroup, a bit of information exchange between users of both products.

Yup. In fact, the whole point of putting pvwave in the name was to let
the PV-WAVE people know that the IDL people were out there (and vice
versa), and worth talking to.

-steve
--
-------------------------------------------------------+"Come, Watson, come!"
 Steve Swales                (716) 275-0265,-3857,-5101| he cried. "The game is
 steve@bat.lle.rochester.edu           (128.151.32.111)| afoot. Not a word!
 {decvax,harvard,ames,rutgers}!rochester!ur-laser!steve| Into your clothes and
 University of Rochester            250 East River Road| come!"		S.H.
 Laboratory for Laser Energetics    Rochester, NY 14623|     'The Abbey Grange'