| IDL (Interactive Data Language) FAQ [message #807] |
Mon, 17 May 1993 06:22 |
pat
Messages: 25
Registered: June 1992
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Junior Member |
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Archive-name: idl-faq
Last-modified: 1993/05/17
Version: $Id: idl-faq,v 1.4 1993/05/17 13:17:58 pat Exp pat $
This is a list of Frequently Asked Questions about the Interactive Data
Language or IDL. These questions pop up fairly regularly in the newsgroup
comp.lang.idl-pvwave. This list is an attempt to cut down on net.traffic
regarding commonly asked questions. Users are encouraged to read through
this list before posting a query to the newsgroup.
A Note from the editor about PV~WAVE:
I do not have any direct experience with PV~WAVE. As such, I will try to
minimize comments which appear to favor one package or the other. I
will, however, welcome concise descriptions of technical and functional
differences between the two packages.
If you are viewing this text in a GNU Emacs Buffer, you can type
"M-2 C-x $" to get an overview of just the questions. Then, when you want
to look at the text of the answers, just type "C-x $".
The following questions are answered:
G01. What is IDL?
G02. Where can I contact them?
G03. How do I get IDL?
G04. What is the current version of IDL?
G05. On what systems does IDL run?
G06. What is PV~WAVE and how is it related to IDL?
G07. Are there anonymous FTP sites for IDL?
G08. How can I get help?
G09. Why are there two newsgroups for IDL?
G10. Does anyone at RSI read this group? Is anyone there listening?
G11. When is the next version of IDL due out?
T01. Why doesn't polycontour fill open contours?
T02. How do I increase the number of commands stored in the
T03. How do I get IDL to call routines in language X, running
T04. Why does XPALETTE edit my color table incorrectly?
T05. Is there on-line help for IDL?
T06. I run IDL under X in SunOS 4.x, and after I logout, the screen
T07. Sometimes my variables seem to disappear. Why is this?
T08. Is there a major mode for editing IDL code in Emacs?
T09. How do I get 3-D widgets under OpenLook 3.0?
T10. Why does one of the widgets appear red under OpenWindows?
T11. Where are all the IDL routines and userlib procedures?
T12. Does anybody know how to put multiple image plots on one page in
T13. Does case matter in IDL?
T14. How do I set up IDL to get precise control over plot window
and text positioning with either portrait or landscape page
orientation on a PostScript or HP-GL printer?
T15. I get the error message "Code Area Full". What do I do?
============================================================
GENERAL:
G01. What is IDL?
IDL is the Interactive Data Language. It is is a product of
Research Systems, Inc. (RSI).
The following is quoted from the README file at rsinc.com:/pub/idl/README.
As such, it describes IDL's capabilities in an understandably subjective
manner. ;-)
{begin quote}
IDL, Interactive Data analysis Language, is a
complete package for the interactive reduction, analysis,
and visualization of scientific data and images. Optimized
for the workstation environment, IDL integrates a responsive
array oriented language with numerous data analysis methods
and an extensive variety of two and three dimensional
displays into a powerful tool for researchers.
IDL supports an extensive data import capability,
publication quality hard copy output, and user-defined Motif
graphical user interfaces.
Users can create complex visualizations in hours
instead of weeks with the aid of IDL's high level capabilities
and interactive environment.
IDL is useful in physics, astronomy, image and
signal processing, mapping, medical imaging, statistics,
and other technical disciplines requiring visualization of
large amounts of data.
{end quote}
Here is a short history of RSI:
[attributed to ali@rsinc.com (Ali Bahrami)]
{begin quote}
IDL is a product of Research Systems, Inc., founded in 1977
by David Stern. The origins of IDL were developed at the Laboratory
for Atmospheric and Space Physics (LASP) at the University
of Colorado. David was one of the people involved in efforts to
make computers easier to use for the physicists at the Lab.
The first program in the evolutionary chain to IDL was named Rufus
(named after Dave's dog). Rufus was a very simple vector oriented
calculator that ran on the PDP-12. It accepted 2 letter codes that
specified (1) An arithmetic operation (2) The input registers to
serve as operands, and (3) the destination register. The next version
was the Mars Mariner Spectrum Editor (MMED) which was a version
of Rufus that ran on the PDP-8.
The next program in this line was named SOL, and it also ran on
the PDP-8. Unlike its predecessors, SOL was a real computer language
with a real syntax (no more 2 letter codes). It was an APL influenced
array oriented language with some primitive graphics capabilities.
The resemblance to IDL was there, but very faintly.
In 1977, Dave left LASP to start Research Systems Inc. (RSI) with the
intention of building on the ideas contained in SOL. The initial
result of this endeavor was PDP-11 IDL, which was much more capable than
SOL. Graphics was usually done on Tektronix terminals and outboard
raster graphics displays. I used this version at LASP in 1981 on a
PDP11/34 under RSX-11M in 1981 (I worked as a student at LASP from
1981 to 1987). I didn't use it for very long though,
because 1981 was the year that Dave released the VAX/VMS version of
IDL. This version, which was written in VAX-11 MACRO and FORTRAN,
took advantage of the VAX virtual memory and 32-bit address space,
and was a huge step beyond the PDP-11 version. It used essentially
the same sort of graphics hardware as the PDP-11.
In 1987, Dave decided that Unix workstations were the direction in
which IDL should progress, but porting the current VAX IDL to Unix
didn't make much sense because of its MACRO and FORTRAN implementation.
I had just finished my Masters degree and was looking for work.
Dave hired me and together we wrote the current version of IDL for
Unix on the Sun 3 taking advantage of the re-write to extend and
improve the language. Since then, we've ported it to many Unix
machines and moved it back to VMS. RSI has many other employees now,
but our focus is still the continued development of IDL. Recently,
IDL was ported to PC class systems running Microsoft Windows.
{end quote}
G02. Where can I contact them?
Their address is:
Research Systems, Inc.
777 29th Street, Suite 300
Boulder, CO 80303
(303) 786-9900 (Voice)
Email:
info@rsinc.com or support@rsinc.com # Internet
ORION::IDL # SPAN
G03. How do I get IDL?
RSI's distribution scheme is unique in that all of the binaries and
IDL you need are available via anonymous ftp. IDL binaries and code are
available at these sites:
gateway.rsinc.com (192.5.156.17)
pub/idl
boulder.colorado.edu (128.138.240.1)
pub/idl
lumpi.informatik.uni-dortmund.de (129.217.36.140)
pub/idl
The README file describes which files are needed, how to unpack them, and
how to install them.
If you install IDL without a valid license, you will get IDL's 7
minute demo mode. This mode is designed for users who are considering
buying the package.
To actually get IDL running for good, you must pay for a license
from RSI and follow their instructions. You will be asked to fill out a
form with information unique to your machine. RSI will create a license
key which the license manager program (lmgrd) reads to validate your
license.
[ Rumor has it that RSI's distribution scheme is soon going to change
in a big way. -pat ]
For more details, contact RSI.
G04. What is the current version of IDL?
Version 3.0.0 is the current version. The next release is expected
around May, 1993.
G05. On what systems does IDL run?
The information below is from the file RELEASE_LEVEL located at
rsinc.com:/pub/idl/RELEASE_LEVEL:
{begin quote}
This release supports the following systems:
- Convex C2 and C3: ConvexOS 10.0.5.
- Data General Aviion: DG/UX 5.4.1 and later
- HP 9000: HP-UX 8.0 on Series 300, 400 and 700.
- IBM 6000: AIX 3.2.
- MIPS: Risc/OS 4.52B.
- Risc Ultrix: Ultrix 4.2.
- SGI: IRIX 4.0
- Sun 3: SunOS 4.1.0. Widgets are built using OpenWindows 2.0.
- Sun 4 (sparc): SunOS 4.1.0. Widgets are built using
OpenWindows 3.0.
- VAX/VMS: The standard release which does not include widgets
requires VMS 5.1 or later. The version including widgets requires
VMS 5.4.
- DOS based personal computers running Microsoft Windows 3.1
{end quote}
There is also a version of IDL which runs on DEC Alphas under
OpenVMS 1.0.
[ This information received 4/6/93. -pat ]
{begin quote}
The IDL port is now available for SUN Solaris 2.1 and for the DEC
Alpha machine running OSF/1.
If you have questions or need more information please send e-mail to
info@rsinc.com or call Research Systems, Inc. at (303) 786-9900.
[] This special release is for these two platforms only and
is known as IDL 3.0.2. It isn't compatible with the current
3.0.0 release, and can't be combined.
[] These platforms will be fully integrated into the next
full IDL release, due in late May.
[] This release is available on the internet for anonymous FTP
from our gateway in pub/idl_3_0_2. It is also available from
boulder.colorado.edu in pub/idl/SOLARIS_AND_ALPHA.
{end quote}
G06. What is PV~WAVE and how is it related to IDL?
Around the time that the Unix version of IDL first became available
(1988), Precision Visuals Inc. (PVI) entered into an agreement with RSI
under which they enhanced and resold IDL under the name PV~WAVE. In
September of 1990, they exercised an option in that agreement that
resulted in the following:
- They received a copy of the IDL source code as it existed in
September 1990 in return for a one-time payment to RSI.
- The connection between RSI and PVI was severed.
IDL and PV~WAVE are now on separate development tracks. Each
company enhances, supports, and maintains its own product.
PVI has since merged with IMSL and is now Visual Numerics, Inc.
(VNI).
G07. Are there anonymous FTP sites for IDL?
The sites below contain public domain IDL code.
JHU/APL IDL library
fermi.jhuapl.edu [128.244.147.14]
/pub/idl-pvwave/jhuapl
NASA IDL Astronomy User's Library
idlastro.gsfc.nasa.gov [128.183.57.82]
/
IUE RDAF library
iuesn1.gsfc.nasa.gov [128.183.57.16]
cetus.colorado.edu [128.138.238.151]
/pub
ICUR Spectral Analysis Software
ftp.astro.psu.edu [128.118.147.28]
/pub/nefftp/icur
IDL ROSAT software
rosserv.gsfc.nasa.gov [128.183.8.43]
/pub/IDL
IDLmeteo library
ftp.sma.ch (141.249.3.33)
/pub/idlmeteo
G08. How can I get help?
RSI has excellent telephone and email support. You can contact
them at:
(303) 786-9900 (Voice)
(303) 786-9909 (Fax)
Email:
info@rsinc.com or support@rsinc.com # Internet
ORION::IDL # SPAN
Keep in mind, however, that their phone support is primarily for their
paying customers.
G09. Why are there two newsgroups for IDL?
Unfortunately, there are two very different packages with the
abbreviation "IDL". The newsgroup comp.lang.idl is for the Interface
Description Language. The newsgroup for discussing issues related to
RSI's IDL and VNI's PV~WAVE and IMSL/IDL is comp.lang.idl-pvwave.
G10. Does anyone at RSI read this group? Is anyone there listening?
[ This question was included at the request of RSI. The answer was
provided by Ali Bahrami. -pat ]
{begin quote}
Yes, many of us do. We're naturally curious what people think of
our product. We make notes about what people like and dislike and
this influences our decisions.
However, you usually won't get a direct response from us from
a posting to this group. There are many reasons for this.
Here are a couple of the more important ones:
[] We believe that this group should belong solely to the
user community, and should be free of vendor bias and
marketing. It should be noted that both RSI and Visual
Numerics (formerly PVI) have shown great restraint in this
matter, and that this group is largely left to the actual
users. (Long term readers will recall some notable exceptions
to this, but in general it is true.)
It could be argued that as long as the topic stays
technical, vendor postings are OK. The problem with this
is that one persons technical posting is another's
blatant product plug, and the line between them is not
always obvious.
[] We provide support for our customers via the phone and email.
If you would like an answer from us, you should
call us directly. We have no objection to you sharing the
information you get in this manner with the newsgroup as
long as you quote us accurately and separate fact from
conjecture.
In other words, you should view this newsgroup as a way to share
questions and information with other users, not as a way to
contact the vendor.
{end quote}
G11. When is the next version of IDL due out?
IDL 3.1 is due out sometime in June. The following information
about comes directly from RSI.
{begin quote}
------------------------------------------------------------ ---------
WHAT'S NEW IN IDL 3.1
------------------------------------------------------------ ---------
This file describes the major changes and additions to IDL in
version 3.1. For a more detailed list of changes, see the file
"rel_note.doc" in the "notes" subdirectory of the IDL distribution.
Note that complete documentation for new routines and features
can be found in the online help, IDL User's Guide, and/or IDL
Reference Guide.
------------------------------------------------------------ ---------
NEW MAJOR FEATURES
------------------------------------------------------------ ---------
CONTOUR IMPROVEMENTS
--------------------
Extensive revisions and improvements have been made to the
CONTOUR procedure. CONTOUR can now create filled contour plots
with a single command. Regions can be filled with either solid
color or lines. The orientation and spacing of fill lines can
be controlled with the C_ORIENTATION and C_SPACING keywords.
Set the FILL keyword to create a filled contour plot. This
functionality makes the POLYCONTOUR Users' Library routine
obsolete.
Also, to make the direction of grade more obvious,
perpendicular tick marks can be drawn pointing in the downhill
direction by setting the DOWNHILL keyword.
The format of the file written by the PATH_FILENAME keyword
has been changed slightly. The XY values are now written as
the n X values followed by the n Y values. Previously, the XY
values were interleaved.
The SPLINE keyword has been removed. In its place, use the
MIN_CURVE_SURF user library function to smooth relatively small
arrays. See the online help for complete documentation on
MIN_CURVE_SURF.
See the online help or IDL Reference Guide for complete
documentation for CONTOUR.
!PATH BEHAVIOR CHANGED
----------------------
When IDL encounters a procedure or function call that it
doesn't know, it searches the directories specified by the
!PATH system variable for a .PRO file with that name. If
no .PRO file is found, IDL searches for a .SAV file (an IDL
SAVE/RESTORE file) of the same name in the hopes that restoring
that file will define the needed routine.
This behavior is described in more detail on p. 2-13 of the
June 1993 edition of the IDL User's Guide.
Note also that a new system function, EXPAND_PATH, can be
used to simplify the specification of paths to be searched.
!HELP_PATH SYSTEM VARIABLE
--------------------------
The new system variable !HELP_PATH lists those directories
where IDL should look for online help files. The same rules
for syntax used for !PATH apply. Previously, the help
subdirectory of the IDL distribution was the sole place searched.
This change allows users to have their own help files without
having to put them in the IDL distribution.
A environment parameter, IDL_HELP_PATH controls the value of
!HELP_PATH at startup.
Complete documentation for this feature can be found on p. 2-21
of the IDL User's Guide.
NESTED CALLS TO EXECUTE
-----------------------
The EXECUTE function now allows nested calls to EXECUTE, removing
the previous restriction that EXECUTE could not call a routine
that used EXECUTE.
KEYWORD INHERITANCE
-------------------
"Keyword inheritance" allows IDL routines to pass keyword
parameters not defined in their declaration on to routines that
they call. This feature greatly simplifies writing "wrapper"
routines (variations on a system or user-provided routine).
If a routine is defined with a formal keyword parameter named
" _EXTRA", pairs of unrecognized keywords and values are placed
in an anonymous structure. The name of each unrecognized keyword
becomes the tag name, and its value is the tag value.
A complete description and example of keyword inheritance can be
found on p. 10-5 of the IDL User's Guide.
WDELETE AND WSHOW AFFECT DRAW WIDGETS
-------------------------------------
WDELETE and WSHOW now work with draw widgets on all platforms. If
the argument sent to either of these procedures is the Widget ID
of a draw widget, the top level base for that widget is either
destroyed (WDELETE) or brought to the front of the screen (WSHOW).
Previously, this behavior was only seen in IDL for Windows.
ISO LATIN 1 FONT ENCODING
-------------------------
Added support to the PostScript driver for fonts using the
Adobe ISO Latin 1 font encoding. Setting the ISOLATIN1 keyword
causes IDL to use this encoding with any font that works with
it. Use of the ISOLatin1 encoding allows rendering characters
commonly found in Latin languages other than English. Two new
user library procedures accompany this new feature:
PS_SHOW_FONTS - Display all the PostScript fonts that IDL
knows about, with both the StandardAdobe and ISOLatin1
encodings. Each display takes a separate page, and each
character in each font is shown with its character index.
PSAFM - Converts a standard Adobe AFM file to one more to
IDLs liking. The AFM files in the ps subdirectory of
the IDL distribution were all generated by PSAFM.
OBLIQUE SLICING
---------------
The IDL SLICER Widget Library procedure can now render oblique
planes (i.e., planes at any angle through the volume).
NEW RPC EXAMPLE FILES
---------------------
Any machine-specific RPC Makefile dependencies have been put
into separate "XXX.def" files which are included in the Makefile
(located in the "rpc" subdirectory of the distribution). This
makes it easier for users to compile.
A new example (idl_client.c in the "examples" subdirectory of the
"rpc" subdirectory) shows how to access an RPC server from IDL
(i.e., how to use IDL as an RPC client). Also included is an
example server (fake_server).
SCIENTIFIC DATA FORMAT EXAMPLES
-------------------------------
A new subdirectory, called "data_fmt" has been added to the "misc"
subdirectory. The "data_fmt" directory contains a number of examples
that illustrate the use of the CDF, netCDF, and HDF interfaces.
GRAPHICS CAPTURE TO CLIPBOARD IN IDL FOR WINDOWS
------------------------------------------------
IDL graphics can now be captured to the Microsoft Windows clipboard.
Access this feature through the edit menu or type Ctrl-G. The
palette and bitmap are copied separately. The interface asks
the user to double-left-click on the appropriate window.
DYNAMIC DATA EXCHANGE CLIENT CAPABILITY IN IDL FOR WINDOWS
----------------------------------------------------------
IDL for Windows now supports DDE *client* capability. This only works
for *cold* DDE links. A number of new system calls, described in
the IDL for Windows Installation Instructions and Release Notes,
have been added to support this feature.
------------------------------------------------------------ ---------
NEW BUILT-IN (SYSTEM) ROUTINES
------------------------------------------------------------ ---------
See the online help and/or IDL Reference Guide for complete
documentation on the new system routines listed below.
SYSTEM FUNCTIONS FOR ROUNDING
-----------------------------
CEIL returns the closest integer greater than or equal to x.
FLOOR returns the closest integer less than or equal to x.
ROUND returns the closest integer to x.
EXPAND_PATH
-----------
EXPAND_PATH accepts a path-definition string (a scalar string
argument that could be used for the IDL_PATH or IDL_HELP_PATH
environment variables), and returns an expanded string, suitable
for assignment to the !PATH or !HELP_PATH system variables.
GRID3
-----
The GRID3 converts 3-dimensional irregularly-gridded data to
a regular grid.
------------------------------------------------------------ ---------
NEW USERS' LIBRARY ROUTINES
------------------------------------------------------------ ---------
See the online documentation (the ? command) for complete
documentation on these new Users' Library routines.
READ AND WRITE MICROSOFT WINDOWS BITMAP (.BMP) FILES
----------------------------------------------------
READ_BMP and WRITE_BMP allow you to read and write Microsoft
Windows device-independent bitmap files (.BMP files).
MINIMUM CURVATURE SURFACE
-------------------------
The MIN_CURVE_SURF function fits a minimum curvature spline
surface to a set of regularly or irregularly-gridded points.
When used with the CONTOUR procedure and with low resolution
arrays, this function produces more accurate and pleasing results
than using the SPLINE keyword to CONTOUR.
NEW PULL-DOWN MENU COMPOUND WIDGET
---------------------------------
A new Widget Library routine, CW_BSELECTOR, is a compound widget
pull-down menu who's button label shows the menu item currently
selected, creating a widget similar to an MS-Windows "combo"
control.
FIND A SPHERE GIVEN 4 POINTS
----------------------------
The SPH_4PNT routine returns the center and radius of a sphere,
given 4 points on the sphere's surface.
EASY CREATION OF ANONYMOUS STRUCTURES
-------------------------------------
The CREATE_STRUCT function creates an anonymous structure
given pairs of tagnames and values, and also concatenates
structures. Tagname parameters can be either scalar strings
or string arrays.
FIX FOR ULTRIX XDR FILES FROM V. 3.0.0
--------------------------------------
In IDL 3.0.0 for the Ultrix DecStation, all XDR output of
double-precision floating-point data has its least and
most significant longwords reversed. This presents no
problem as long as such files are only used on these machines.
However, XDR files with double precision data cannot be
moved between these machines and others without conversion
using the new library procedure MIPSEL_DBLFIXUP to correct
existing files containing such data.
This error exists in version 3.0.0 of IDL only. All other
versions of IDL on the DECstation work correctly. This bug
was introduced while correcting the similar bug described on
11/12/92.
IDL uses XDR for Save/Restore files, and for files opened
with the XDR keyword to OPENR, OPENW, and OPENU.
------------------------------------------------------------ ---------
NEW KEYWORDS TO EXISTING ROUTINES
------------------------------------------------------------ ---------
This section lists new keywords for existing built-in routines.
See the online help or the IDL Reference Guide for complete
documentation of these new keywords.
COLOR_QUAN
----------
New keywords allow the use of the same color mapping
for a series of images:
GET_TRANSLATION
TRANSLATION
MAP_ALL
DEFSYSV
-------
Set the EXISTS keyword to sense if the specified system
variable has already been created.
DEVICE
------
The SET_CHARACTER_SIZE keyword (available to all graphics
devices) can be used to set an arbitrary character size.
The CURSOR_IMAGE and CURSOR_MASK keywords allow the use of
custom cursors with the X Windows DEVICE command.
HISTOGRAM
---------
The INPUT keyword sends an array to be added to the output of
HISTOGRAM. Use this keyword to perform multiple histograms.
The REVERSE_INDICES keyword returns a list of lists containing,
for each histogram bin, the subscripts of the original array
contributing to that bin.
IOCTL
-----
The following keywords have been added for use with magnetic tape:
MT_OFFLINE, MT_REWIN, MT_SKIP_FILE, MT_SKIP_RECORD,
MT_WEOF
OPEN
----
The NOSTDIO keyword has been added for working with magnetic
tape.
READU and WRITEU
----------------
The TRANSFER_COUNT keyword returns the number of elements
actually transferred by an I/O operation.
SHADE_SURF
----------
The MAX_VALUE keyword allows the creation of missing data plots.
SPAWN
-----
The NOTTYRESET keyword allows the use of spawn on displays that
suffer from dropped characters.
SURFACE
-------
The SHADES keyword allows a multi-colored mesh.
WIDGET_CONTROL
--------------
The WIDGET_TIMER keyword replaces the background task
functionality in XMANAGER.
The NO_COPY keyword can be used to set and get uservalues
without duplicating memory.
The TLB_SET_TITLE keyword allows the title of a top level
base to be changed.
------------------------------------------------------------ ---------
NEW UPDATE POLICY
------------------------------------------------------------ ---------
RSI is implementing a new telephone support and update
policy with the release of IDL 3.1. In the past it was possible
for users who did not purchase a maintenance contract to receive
the latest version of the software simply by downloading it over the
network. The newest IDL version would run with old license files.
That is no longer the case, beginning with IDL 3.1.
Users may still download the latest version of IDL from the Network,
but IDL 3.1 will not run with old license files. Users who have
current maintenance and support contracts on their IDL licenses will
receive new license files at no charge simply by asking for them.
Users who do not have support contracts and who wish to update
to IDL 3.1 must purchase an update contract for each IDL license they
wish to update. An update contract entitles you to free maintenance
updates (what we think of as bug fixes and other minor updates) at no
additional charge for a period of one year for that license. Users having
an update contract will be entitled to substantial discounts on major IDL
updates if one should occur during the year in which they have a contract.
The price of a update contract depends upon which machine version of IDL
you are updating. IDL for Windows updates will be $150. IDL updates for
most Unix platforms will be $250. IDL updates for DEC workstations will be
$450. Users do not have to update to IDL 3.1, nor do they have to update
all of their licenses to IDL 3.1. Only the licenses that are updated
will run IDL 3.1. There will be no discounts for multiple licenses.
Telephone support will be priced separately at $200 per person
per year. To ensure quality phone support for our paying customers,
RSI Technical Support Engineers will, beginning June 2nd, only answer
telephone and email questions from those customers who have purchased
a support contract. (New IDL workstation licenses will still come
with six months of update maintenance and phone support.) There will
be a requirement that at least one person at an installation site have a
current telephone support contract in order to purchase an update for
a license at that site.
The purpose of our new update and support policy is to make it
possible for us to continue to provide quality technical support
for IDL on multiple platforms and to continue to add to and improve
IDL. RSI is moving forward with new ports (e.g., the Macintosh), new
services (e.g., IDL Training and Smart Start Consulting), new products
(to be announced this summer) and a new building (somewhere in Boulder)
so that we can be the leader in data analysis and visualization software.
{end quote}
============================================================
TECHNICAL QUESTIONS:
Note for Sun users:
There is a mini FAQ for Sun IDL in $IDL_DIR/notes, and the following
questions are answered in the file openwin3.doc:
(1) IDL complains about missing fonts when creating widgets.
(2) IDL complains about missing bitmap files when creating widgets.
(3) How to make IDL work with OpenWindows version 3.0.
(4) 3-D appearance for OpenLook IDLwidgets.
(5) Why does one of the widgets appear red?
(6) Why does pressing the left button while pointing at a pulldown menu
button cause the menu to pop up with the pushpin in? Older versions of IDL
didn't to that.
(7) The font used by the list widget is much larger than it used to be, and
I don't like the result on my program.
(8) Why do I get "Cannot allocate colormap entry" errors, and why do they
kill IDL?
(9) I've changed my .Xdefaults file, but nothing different happened. Why?
T01. Why doesn't polycontour fill open contours?
This problem is described in the POLYCONTOUR manual page.
{begin quote}
RESTRICTIONS:
This routine will NOT draw open contours. To eliminate open
contours in your dataset, surround the original array with a 1-element
border on all sides. The border should be set to a value less than
or equal to the minimum data array value.
For example, if A is an (N,M) array enter:
B = REPLICATE(MIN(A), N+2, M+2) ;Make background
B(1,1) = A ;Insert original data
CONTOUR, B, PATH=Filename ... ;Create the contour file.
{end quote}
Sources at RSI tell me that they are aware of the problem. It may or may
not be fixed in the next release. It will probably take the form of a
new version of CONTOUR that has a parameter to turn on filled contours.
T02. How do I increase the number of commands stored in the
history buffer?
The system variable !EDIT_INPUT controls command recall. By
default, it is set to 1, causing the last 20 commands to be saved. If it
is 0, no commands are saved. To save more than 20 commands, just put
!EDIT_INPUT=50 (or other large number) in your startup file.
It is important to realize that IDL looks at the value of
!EDIT_INPUT the first time it reads anything from the keyboard, and the
size of the history buffer is fixed after that. Hence, the command must
be in a startup file because entering it at the keyboard is too late.
T03. How do I get IDL to call routines in language X, running
under system Y?
Jeff Valenti has written a sizable document about calling external
FORTRAN routines from IDL. You can find it at jaameri.gsfc.nasa.gov:
/pub/idl/idl-fortran.
T04. Why does XPALETTE edit my color table incorrectly?
Here is the answer from RSI support:
{begin quote}
The color applications such as xpalette and xloadct use a common block
called "colors" to keep track of the color vectors. When you call tvlct,
your vectors are loaded into the colormap, but they are not put into the
colors common block.
When xpalette starts, it checks to see if the colors have been defined in
the common block and uses them if they have. Otherwise it sets them to
the standard black and white colormap, in which r,g,b are each linear
ramps. (The colors are as you expect because there is only one colormap.)
Admittedly, this is not the most desirable situation. You would like
your colors which you loaded with TVLCT to be recognized by xpalette. We
modified xpalette (and xloadct) to use the current colormap when they
start up by getting the current vectors with TVLCT.
Another alternative would be to use the following lines to define the
common block prior to calling your current version of xpalette.
[ assume here that you have a routine called "restore" which reads colors
from a file somewhere and creates vectors r, g, and b. -pat ]
IDL> restore, file='ryan.sav', r, g, b ;get the vectors from somewhere
IDL> tvlct, r, g, b
IDL> common colors, r_orig, g_orig, b_orig, r_curr, g_curr, b_curr
IDL> r_orig = r & r_curr = r
IDL> g_orig = g & g_curr = g
IDL> b_orig = b & b_curr = b
IDL> xpalette
{end quote}
T05. Is there on-line help for IDL?
Try ?.
T06. I run IDL under X in SunOS 4.x, and after I logout, the screen
becomes completely blank. Typing in login names and passwords 'blindly'
logs you in again with the 'correct' colors. How to prevent this?
[Note: This is only a problem under OpenWindows2. -pat ]
Add the following to your .Xdefaults:
Idl*colors: -5
which reserves some colors for the colormap so that IDL does not exhaust
all the available colors. (For a nice summary of Sun IDL interactions
with OpenWindows, see $IDL_DIR/notes/openwin3.doc)
Another solution is to put a call to clear_colormap in your .login
file to be executed after OpenWindows start up.
T07. Sometimes my variables seem to disappear. Why is this?
Quoting the IDL User's Guide, page 10-8:
{begin quote}
IDL users may find that all their variables have seemingly disappeared
after an error occurs inside a procedure or function. The misunderstood
subtlety is that after the error occurs, IDL's context is inside the called
procedure, not in the main level. Typing RETALL or RETURN will make the
lost variables reappear.
RETALL is best suited for use when an error is detected in a procedure and
it is desired to return immediately to the main program level despite
nested procedure calls. RETALL issues RETURN commands until the main
program level is reached.
The HELP command can be used to see the current call stack (i.e., which
program unit IDL is in and which program unit called it).
{end quote}
T08. Is there a major mode for editing IDL code in Emacs?
No and yes.
VNI has developed a PV~WAVE major mode, which they have made
available under the FSF copyleft. Given the (remaining) strong similarity
between PV~WAVE and IDL, it has many of the features that one would like
in such a mode.
It is available by anonymous ftp from ftp.pvi.com (128.138.213.22) in
the ./PVI/emacs directory
[ wave-mode.el seems to work pretty well. Be warned, however, that it is
a memory hog and it will do a lot of garbage-collection. -pat ]
T09. How do I get 3-D widgets under OpenLook 3.0?
This subject is discussed on page 53 of the OpenWindows Version 3
User's Guide Release Manual.
OpenWindows 3.0 added 3-D appearance for widgets. In order for
the 3-D look to work, it must be enabled and the background color
must be a medium tone color such as "grey" or "wheat".
Add the following resources to your ~/.Xdefaults file:
For plain IDL:
Idl*threeD: TRUE
Idl*background: PeachPuff2
For IMSL/IDL:
Imslidl*threeD: TRUE
Imslidl*background: PeachPuff2
T10. Why does one of the widgets appear red under OpenWindows?
This subject is discussed on page 53 of the OpenWindows Version 3
User's Guide Release Manual.
The OLIT widget toolkit, which is used by IDL, added the
concept of "mouseless focus" under version 3.0. The red widget
indicates where the current mouseless focus is. Use the arrow keys
to traverse the widgets, and the spacebar to make a selection.
T11. Where are all the IDL routines and userlib procedures?
The basic routines are not accessible, for obvious reasons. The userlib,
statlib and widget procedures are in $IDL_DIR/lib/. The procedure XDL also
displays the full pathname. The system variable !path also contains the
directory names for all accessible IDL procedures.
T12. Does anybody know how to put multiple image plots on one page in
PostScript?
Because PostScript has scalable pixels, you must specify the xsize and
ysize parameters, as well as the position parameter, in TV or TVSCL.
I don't know about PV-Wave, but the following works in IDL:
; Display four images in a 2x2 grid
; Assume data(x,y,4) = array containing the 4 images
set_plot, 'ps' ;request PostScript output
device, ... ;modify page size, orientation, etc. as desired
ximsize = 0.5*!d.x_size ;define output image size
yimsize = 0.5*!d.y_size ;note: 0.5 assumes 2x2 grid
for i=0,3 do begin ;display the 4 images, using i as position index
tv, data(*,*,i), i, xsize=ximsize, ysize=yimsize
endfor
T13. Does case matter in IDL?
No.
Compiled routines are case insensitive. The only catch is that, on
Unix systems, when executing a script via the .RUN command, the file name
argument must exactly match the file name as it appears on the disk.
Once the routines in the script are compiled, their names can be written
in any case. This is not a problem in operating systems such as VMS that
do not distinguish case for file names. This is usually not a problem
under Unix either since, by convention, most people use lower case file
names.
T14. How do I set up IDL to get precise control over plot window
and text positioning with either portrait or landscape page orientation
on a PostScript or HP-GL printer?
(This answer only applies to PostScript and HP-GL printers --
other printers may differ in having the X and Y offsets measured from
the upper left corner of the portrait page instead of the lower left
corner.)
IDL uses portrait page orientation as a default. (The x axis is along
the shorter dimension of the paper.) In portrait orientation the lower
left corner of the page is the origin for the XOFFSET and YOFFSET page
offsetting keywords of the DEVICE command that determine the origin
(lower left corner) of the output window. (Normally one uses XOFFSET=0
and YOFFSET=0 for portrait orientation.) Size of the output window is
determined by the XSIZE and YSIZE keywords of the DEVICE command.
The origin for graph positioning variables !P.POSITION and !P.REGION
is the output window origin. X and Y coordinates for portrait page
orientation are shown on the sketch below as upper case X and Y.
----------
| | ORIGINAL PORTRAIT PAGE (Printer only prints on
Y | | OUTPUT WINDOW this area.)
| |
| X |
o-----------
| y + | OUTPUT WINDOW ROTATED ABOUT LOWER LEFT CORNER
x | + |
| + |
------------
++++++++++ OUTPUT WINDOW RESIZED FOR LANDSCAPE ORIENTATION
^
| DIRECTION OF NEEDED OFFSET
If device,/landscape is specified, then the output window is rotated
90 deg. clockwise about the lower left corner of the page.
In this condition nothing will be plotted on the page, since the
rotation has carried the output window entirely off the paper as shown
in the sketch above. To correct this mismatch, the rotated output window
must be offset. XOFFSET AND YOFFSET are still measured in the X and Y
coordinates of the portrait page, but now represent the position of the
lower left corner of the rotated (and resized) output window (marked by
an o above) with respect to the lower left corner of the portrait (actual)
page. Hence, one generally uses XOFFSET=0 and
YOFFSET=long_dimension_of_page for landscape orientation.
In landscape orientation, the coordinates for graph positioning variables
!P.POSITION and !P.REGION are the lower case x and y coordinates
shown in the sketch above and having origin marked by the letter o.
Position of output window origin o on the page is, of course, affected
by the setting of XOFFSET and YOFFSET, as explained before. The XSIZE
and YSIZE (output window size) keywords of the DEVICE command are also
measured in the x and y directions when in landscape orientation. The
resizing of the landscape page generally means interchanging the values
of XSIZE and YSIZE appropriate for the portrait page.
Example of settings for a portrait page:
XPAGE=8.5 & YPAGE=11. & XOFFS=0. & YOFFS=0. ;Inches
DEVICE,/INCHES,XSIZE=XPAGE,YSIZE=YPAGE,XOFFSET=XOFFS,YOFFSET =YOFFS
Example of settings for a landscape page:
XPAGE=11. & YPAGE=8.5 & XOFFS=0. & YOFFS=XPAGE ;Inches
DEVICE,/LANDSCAPE,/INCHES,XSIZE=XPAGE,YSIZE=YPAGE,XOFFSET=XO FFS, $
YOFFSET=YOFFS
Example of setting position and size of a plot window:
X0=1.374 & Y0=1.283 & XLEN=3.622 & YLEN=6.157 ;Inches
!P.POSITION=[X0/XPAGE,Y0/YPAGE,(X0+XLEN)/XPAGE,(Y0+YLEN)/YPA GE]
Example of setting position and orientation of a text string:
x0=.35 & y0=.37 ;Inches
xyouts,x0/xpage,y0/ypage,!stime,orient=90,/normal ;Date, time
T15. I get the error message "Code Area Full". What do I do?
IDL sets aside a certain amount of memory area for compiling programs. The
current code and area sizes can be seen with the HELP command, e.g.
IDL> help
% At $MAIN$ .
Code area used: 0% (0/16384), Symbol area used: 0% (2/4096)
These sizes can be increased with the .SIZE command. Quoting the IDL User's
Manual, page 2-11:
{begin quote}
These sizes represent a compromise between an unlimited program space and
conservation of memory. User procedures and functions are compiled in this
large program area. After successful compilation, a new memory are of the
required size is allocated to contain the newly compiled program unit.
Resizing the code and data areas erases the currently compiled main program
and all mail program variables. For example, to extend the code and data
areas to 30000 and 5000 bytes respectively:
.SIZE 30000 5000
{end quote}
Getting "Code Area Full" is often an indication that the routine is
large, and would benefit by decomposition into sub-procedures/functions.
It's better to avoid use of .SIZE because your code will always work on
other systems where the users don't use a large .SIZE setting.
============================================================
Disclaimer:
I do not work for RSI and I am in no way answerable to them. Questions and
answers in this document are culled from the user community. No warranty,
express or implied exists regarding this document. Permission to copy all
or part of this work is granted, provided that the copies are not made or
distributed for resale.
This file can always be found at jaameri.gsfc.nasa.gov [128.183.88.75]
in pub/idl/idl-faq.
Additions and corrections should be sent to:
idl-faq@jaameri.gsfc.nasa.gov
-----
Many thanks to the following for their contributions.
black@breeze.rsre.mod.uk (John Black)
claflin@claes.space.lockheed.com (Scott Claflin)
edelsohn@npac.syr.edu (David Edelsohn)
fireman@iuegtc.DNET.NASA.GOV (Gwyn Fireman)
gurman@umbra.gsfc.nasa.gov (Joseph B. Gurman)
jdlb@kukui.IFA.Hawaii.Edu (JF Pitot de La Beaujardiere)
kashyap@oddjob.uchicago.edu (Vinay Kashyap)
oet@maz.sma.ch (Thomas Oettli)
rmmoss@Texaco.COM (Robert M. Moss)
sterne@dublin.llnl.gov (Philip Sterne)
thompson@serts.gsfc.nasa.gov (William Thompson)
valenti@soleil.Berkeley.EDU (Jeff Valenti)
--
patrick m. ryan
nasa / goddard space flight center / oceans and ice branch / hughes stx
pat@jaameri.gsfc.nasa.gov / patrick.m.ryan@x500.gsfc.nasa.gov
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