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IDL Miscellaneous Programs

XATT_EL - Compute X-ray attenuation coefficient from NIST tables

This function computes the X-ray mass absorption coefficient for a given element, based on the NIST mass absorption coefficients. These tables are most well sampled for energies between 1 keV and 100 MeV. These coefficients are from the tables at:

The user specifies the atomic elements, either by the atomic symbol (as a character string), or by the atomic number (Z). The transmission of a medium is then defined by:

where MU_RHO is the value returned by this function (cm^2/g), RHO is the mass density of the medium (g/cm^3), and THICKNESS is the thickness of the material (cm). All cross section data are stored within the source code file (in a compressed form, translated unchanged from the NIST database).

Dec 21 2011373 kb  

CMUNIQUE_ID - Generating unique identifiers

CMUNIQUE_ID returns a "unique" 8 character identifier. Programmers can use this routine to derive unique strings which can be used to write files, etc.

Identifiers are "unique" in the sense that it is unlikely that two identifiers in a given IDL session will coincide. Thus the identifier is useful for constructing temporary filenames and other hash values. User routines are encouraged to append other identifying information to this string, such as a session id, a hostname, or a process id number.

Jan 12 20013 kb  

DXDEBUG - Command line debugging made easy

Command line debugging with IDL has always been difficult. It does provide excellent abilities to interactively query and set variables, but only at one level -- the deepest level. Generally, when debugging a larger suite of programs one can have procedures and functions that nest several levels deep. Since one procedure can call another, or even itself, this is a natural effect. If an error occurs in a procedure several levels deep, knowing the values of variables at higher levels (i.e., the calling routines) can be useful and time saving. Unfortunately IDL has no documented provisions for doing this.

The procedures in the package supply convenience routines for navigating up and down the IDL call stack (DXUP and DXDOWN); for interogating and modifying IDL variables at any levels in the call stack (DXHELP, DXPRINT, DXGET, DXSET); and for quickly setting and clearing breakpoints (DXBREAK, DXFINISH and DXCLEAR). The package is based upon invaluable discussions about the undocumented ROUTINE_NAMES() function on the comp.lang.idl-pvwave Usenet newsgroup.

Please read DXREADME, which contains general instructions on how to get started degugging.

Dec 08 20009 kb DXREADMEGeneral Documentation  
Apr 30 20017 kb  
Feb 08 20011 kb  
Apr 30 20018 kb  
Jul 01 20013 kb  
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Dec 06 20031 kb INSTALL  

You can download the entire DXDEBUG package as an archive here:

Dec 08 20009 kb DXREADMEGeneral Documentation  
Dec 06 20031 kb INSTALLInstallation Instructions  
Oct 02 201224 kb dxdebug.tar.gz  
Oct 02 201234 kb  

CMSYSTIME - Compute and convert between time representations

CMSYSTIME serves two functions. It computes the current time in a fashion similar to the built-in IDL system function SYSTIME(). It also can convert between various time representations and systems, including a textual format.

The current time can be obtained by invoking CMSYSTIME with the /NOW keyword (which is entirely equivalent to SYSTIME(1)).

The most substantial part of CMSYSTIME, which distinguishes it from SYSTIME, is its ability to convert between different time formats. CMSYSTIME recognizes can recognize and convert between time in seconds (seconds since Jan 1, 1970 [ = SEC ]) and days (Julian days [ = JDAY ] or "Modified" Julian days [ = MJD = JDAY - 2400000.5 ]). It can also recognize and convert between local and GM time. The local time zone is determined automatically.

CMSYSTIME takes maximum care to preserve the full numerical precision of the time values. It converts all values to double precision and may return days and seconds with fractional parts. CMSYSTIME accepts one parameter, the input time to be converted. Unlike SYSTIME, the *function* of CMSYSTIME is governed by various keywords, as summarized in the following table:

Converting from                       Converting to
---------------                       -------------
JDAY - /FROM_JULIAN                   JDAY - /JULIAN
MJD  - /FROM_MJD                      MJD  - /MJD
SEC  - (Default)                      SEC  - /SECONDS
Current time - /NOW                   TEXT - (Default or /EXTENDED)

Local time - /FROM_LOCAL              Local time - /LOCAL
GM time - (Default)                   GM time - (Default)
Dec 29 200511 kb  

STATUSLINE - Maintain a one-line status line (Unix/ANSI)

I find this routine very useful on Unix systems for performing continuous status updates during long calculations. This routine performs a similar function to the "percentage completion" status widget that you often find under Windows or MacIntosh.

STATUSLINE interacts directly with the terminal console to perform character addressing, which must be VT100, XTerm, ANSI, or compatible.

Jul 14 20077 kb  

CMCONGRID - Improved image interpolation

This is a modified version of CONGRID.PRO, supplied in the IDL distribution. The original CONGRID does not handle the edge conditions properly, either with or without the MINUS_ONE keyword. The problem is noticeable when small images are resampled to be very large images, since an "extra" column and row is added at one side of the image. With the MINUS_ONE keyword, a coordinate grid cannot be properly overlayed.

This version can be used in place of the original CONGRID, and defines a new keyword called HALF_HALF which does the correct interpolation. "Half" of an extra row and column are added to both sides of the image, making it properly symmetric. A coordinate system can also be overlayed correctly. TVIMAGE is a slightly modified version of David Fanning's procedure, which takes advantage of the new CMCONGRID.

I assert that the output of CMCONGRID with the HALF_HALF keyword is always more correct than that of CONGRID alone. And now, with a bug fix from Wayne Landsman, it's even more correct! The correction is most apparent when down-sampling.

Jul 14 20076 kb  
Dec 31 19690 kb tvimage.proRequires CMCONGRID  

Copyright © 1997-2010 Craig B. Markwardt
Last Modified on 2017-01-03 13:57:28 by Craig Markwardt