Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
Re: On the differences between idl and pvwave
In article <51116@netnews.upenn.edu> yee@mipgsun.mipg.upenn.edu (Conway Yee) writes:(only slightly trimmed) > > From what I understand, the company that markets pvwave licensed > idl and markets it under their own name. In the near future, my > lab will be purchasing idl/pvwave. From what I can see, the two > are identical products. What are the essential differences between > the two and which should we buy? At the National Severe Storms Lab we have IDL. My local university, which shall go unnamed, bought PVWAVE. They are indeed 99% the same product. The essential differences: Graphics commands especially go by the 'keyword' concept in PVWAVE, while IDL goes (VAX version) by 'parameters': IDL> CONTOUR,agrid,[1,2,5,10,20,50,100] WAVE>CONTOUR,agrid,labels=[1,2,5,10,20,50,100] The latter is too much typing for an INTERACTIVE programming language IMO. I also believe that the former is better for 'sophisticated' programming where you might build commands then execute them (if you are so inclined). Also, both come with a 'user library', sort of a small scale IMSL-like set of routines. IDL's is useful. PVWAVE's was full of bugs. PVWAVE comes with a 'window based tutorial' which I found simply a nuisance. The way to learn IDL, like any programming language, is by cloning some short and sweet programs that do typical things (I have such a set of screen size programs that do elementary plotting, contouring, map drawing, map plotting, basic image things, etc...call me). I could ramble a long time on this. IDL is a good scientific programming language. I used to use FORTRAN, now I use IDL. I am willing to provide information, ranging from getting a sample manual to you, to sending real programs that do real science. Dave Keller "I own no stock in Research Systems Incorporated"
|>At the National Severe Storms Lab we have IDL. My local university, which |>shall go unnamed, bought PVWAVE. |>They are indeed 99% the same product. |>The essential differences: |>Graphics commands especially go by the 'keyword' concept in PVWAVE, while |>IDL goes (VAX version) by 'parameters': |> IDL> CONTOUR,agrid,[1,2,5,10,20,50,100] |> WAVE>CONTOUR,agrid,labels=[1,2,5,10,20,50,100] |>The latter is too much typing for an INTERACTIVE programming language IMO. |>I also believe that the former is better for 'sophisticated' programming |>where you might build commands then execute them (if you are so inclined). |> |>Also, both come with a 'user library', sort of a small scale IMSL-like |>set of routines. IDL's is useful. PVWAVE's was full of bugs. |> |>PVWAVE comes with a 'window based tutorial' which I found simply a nuisance. |>The way to learn IDL, like any programming language, is by cloning some |>short and sweet programs that do typical things (I have such a set of |>screen size programs that do elementary plotting, contouring, map drawing, |>map plotting, basic image things, etc...call me). |> |>I could ramble a long time on this. IDL is a good scientific programming |>language. I used to use FORTRAN, now I use IDL. I am willing to provide |>information, ranging from getting a sample manual to you, to sending real |>programs that do real science. |> |>Dave Keller "I own no stock in Research Systems Incorporated" |> |> We, this certainly deserves a response (being we are the local University that bought PVWAVE). 1). For people who know PVWAVE, one does not have to use keywords but can achieve the same 'parameter' effect of IDL by programming the procedure appropriately...so this point is invalid. The keyword concept is both useful and good. It provides a way of checking if a parameter is present and providing a default if it is not present. Furthermore, if all one does is interactive programming, then the user/"programmer" loses much of the power and flexibility of both systems. 2) PVWAVE comes with a much larger library than IDL which I have found to be vary useful and since I have used PVWAVE quite a bit, I have found only a few bugs (no more than most software, and their tech support has been very helpful). I can not speak for IDL, but I doubt Dave can speak for PVWAVE. 3) PVWAVE's tutorial in windows can be a bit sluggish at times, but hey...windows are not anybody's race horse...and after all, both systems are little more than an interpretive compiler which are not speed daemons in themselves, verses compilers that generate machine code. PVWAVE supplies many of the "sweet" programs that Dave has but are supported and probably better written. 4) IDL/PVWAVE are good for basic data manipulation and graphs, for anyone who does real scientific work, I would suggest doing most of your computations in FORTRAN or any other such language for speed and generate a file of data or graph points and use one or more of these tools for final analysis. I doubt any reasonable person who does any large or medium scale computing would advocate replacing FORTRAN et.al. with IDL or PVWAVE. I don't advocate IDL over PVWAVE or vice versa. Precision Visuals did a very good job of marketing their product and we've been happy with what we have and I use PVWAVE frequently for a variety of used and has been invaluble in many cases for graphics for Master/PhD thesis/dissertations as well as image processing. It appears to me that both products are good and useful. They are now on separate development paths since they have ended their business relationship. Find the one that best fits your economic and computing needs and choose it. Lets get rid of this needless tirade/boring discussion of which is better much less what their differences are (at least until later products). Both have the same capabilites for the most part. Pax ------------------------------------------------------------ ---------------- Dwight D. Moore Geosciences Computing Network University of Oklahoma dwight@geohub.gcn.uoknor.edu Sorry, no cute quotes this time. Oh hell, what the heck...I don't own stock in either IDL or Precision Visuals. Geosciences Computing Network University of Oklahoma dwight@geohub.gcn.uoknor.edu (129.15.40.10) These opinions do not necessarily represent the opinions of OU or the GCN. (Sorry to disappoint you, no cute quote this time.) ------------------------------------------------------------ ----------------
Just this morning I noticed another difference between IDL and WAVE -- WAVE is supposed to support CGM output whereas IDL does not claim to. Unfortunately, it turns out that the WAVE CGM does not conform to the standard. This is a problem for me, as the software that drives our film recorder supports CGM, but chokes on the files from WAVE. The film recorder does not support any of the other formats written by IDL or WAVE. I was hoping RSI would have solved the non-standard CGM problem, but CGM is not listed in the supported "devices." Has anyone come up against this problem, or have any suggestions for me? Thanks, Jennifer Dungan jennifer@vessna.arc.nasa.gov TGS Technology Inc. MS 242-4 NASA/GSFC Moffett Field, CA 94035 (415) 604-3618
IDL has keyword parameters too, in version 2.0. I believe it is backward compatible and can still understand the non-keyword versions of commands too. It has been my experience that IDL customer support is very responsive. It would be interesting to know how the whole thing with IDL/PV-WAVE happened-- seems kind of strange! Linda Hunt
In article <1991Sep20.192502.9749@news.arc.nasa.gov> jennifer@gaia.arc.nasa.gov (Jennifer Dungan) writes: > Just this morning I noticed another difference between IDL and WAVE > -- WAVE is supposed to support CGM output whereas IDL does not claim > to. Unfortunately, it turns out that the WAVE CGM does not conform (other lines delete) Actually, IDL produces NCAR Graphics Metacode files which are CGM files. I'll bet the WAVE code is the same, but they may have "improved" it. My limited experience with the NCAR CGM files are that they were fine except their text size has a bug (or is non-standard CGM) -- text which looks fine from NCAR routines is tiny from CGM translators.
In article <1991Sep20.031251.29717@uokmax.ecn.uoknor.edu>, keller@nsslsun.nssl.uoknor.edu (Dave Keller) writes... > Graphics commands especially go by the 'keyword' concept in PVWAVE, while > IDL goes (VAX version) by 'parameters': > IDL> CONTOUR,agrid,[1,2,5,10,20,50,100] > WAVE>CONTOUR,agrid,labels=[1,2,5,10,20,50,100] > The latter is too much typing for an INTERACTIVE programming language IMO. > I also believe that the former is better for 'sophisticated' programming > where you might build commands then execute them (if you are so inclined). You're using an *OLD* version of IDL. This is comparing apples and oranges. Keywords originated in IDL (version 2) before IDL and PVWAVE split apart. Keywords are an immensely useful concept. The sophistication of my IDL software has increased exponentially since keywords were introduced. It is a hell of a lot easier for *OPTIONAL* information to propagate through a chain of subroutines if the keyword concept is used. Bill Thompson