Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uflorida!haven!aplcen!warper.jhuapl.edu From: gotwols@warper.jhuapl.edu (Bruce Gotwols) Newsgroups: comp.lang.idl-pvwave Subject: Difference between IDL and PV-WAVE Explained Message-ID: <5944@aplcen.apl.jhu.edu> Date: 14 Jul 90 21:59:37 GMT Sender: news@aplcen.apl.jhu.edu Reply-To: gotwols@warper.jhuapl.edu (Bruce Gotwols) Organization: JHU-Applied Physics Laboratory Lines: 40 Nntp-Posting-Host: warper.jhuapl.edu 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)