Contents of IDL Astronomy User's Library

• Astronomical Utilities
• DAOPHOT-Type Photometry Procedures
• Database Procedures
• Disk I/O (MIDAS, IRAF files)
• FITS Astrometry and Calibration
• STSDAS modified FITS Image manipulation
• FITS ASCII Table I/O
• FITS Binary Table Extensions I/O
• FITS I/O
• Image Manipulation
• Math and Statistics
• Plotting Procedures
• IDL Structure procedures
• STSDAS (Binary) Table I/O
• Tape IO Procedures (Unix and VMS only)
• TV Display Procedures
• Miscellaneous (Non-Astronomy) Procedures

• README
• A_b() Compute interstellar extinction in the B band as a function of galactic position (as in RC2 catalog, deVaucoulers).
• ADSTRING() Format RA and DEC as a character string
• AIRTOVAC Convert air wavelengths to vacuum wavelengths
• AITOFF Convert longitude,latitude to X,Y using Aitoff equal-area projection
• AITOFF_GRID Create an overlay grid using the AITOFF projection
• ARCBAR Draw an arcbar over an image showing the astronomical plate scale
• ARROWS Given a FITS header, display a "weathervane" showing N-E orientation
• ASTDISP Display formatter for pixel + astronomical coordinates
• ASTRO Interactive driver to compute astronomical precession, or coordinate conversions (calls EULER and PRECESS).
• BARYVEL Compute components of barycentric Earth velocity, given Julian date
• BPRECESS Precess coordinates, proper motion from J2000 to B1950
• CCM_UNRED Deredden a spectrum using the Cardelli, Clayton and Mathis (1989) parameterization.
• CT2LST Convert from civil time to local sidereal time
• DATE() Convert day of year to a DY-MON-YR string
• DATE_CONV() Function to perform various date format conversions
• DAYCNV Convert from Julian Date to calender date.
• DEREDD Deredden Stromgren indices (called by UVBYBETA)
• EQPOLE Convert longitude,latitude to X,Y using polar equal-area projection
• EQPOLE_GRID Create overlay grid using polar equal-area projection
• EULER Astronomical coordinate system conversions
• FLUX2MAG() Convert from flux units to magnitudes
• GAL_FLAT() Correct a galaxy image for inclination effects.
• GCIRC Compute rigorous great circle distance
• GET_COORDS Read in angular input in decimal or sexigesimal format
• GET_DATE Get the current date in DD/MM/YY format (FITS standard)
• GET_JULDATE Get the current Julian date as a double precision scalar
• GLACTC Convert between galactic and equatorial coordinates at any equinox
• HELIO Compute (low-precision) heliocentric coordinates of the planets
• HELIO_JD() Convert geocentric (reduced) julian date to heliocentric julian date
• HELIO_RV() Compute radial velocity given binary star orbit parameters
• IMCONTOUR Contour plots with astronomical labeling (either RA,Dec or arc distance from the image center
• IMF() Return values for a multi-component power law initial mass function
• ISMEUV() Compute EUV optical depth due to photionization of HI, HeI and HeII
• JDCNV Convert from calender date to Julian date.
• JPRECESS Precess positions & proper motions from B1950 to J2000
• JULDATE Convert from calender date to reduced Julian date.
• MAG2FLUX() Convert from magnitudes to flux units
• MOONPOS Compute the RA and Dec (and distance) of the moon at a given date
• MPHASE Compute illuminated fraction of the Moon's disk for given Julian dates
• NUTATE Compute the nutation in longitude and latitude for given Julian date(s)
• PLANCK() Returns a blackbody flux for a given effective temperature
• PRECESS Precess RA and Dec to a new equinox
• PREMAT() Returns precession matrix from equinox 1 to equinox 2
• QDCB_GRID Create overlay grid using COBE quad cube database coordinates
• RADEC Format RA, Dec as Hours,Min,Sec,Deg,Min,Sec
• REDSHIFT Interactively convert between redshift, distance, and velocity (in /jhuapl)
• SIXTY Convert decimal number to sexigesimal
• SPHDIST() Find angular distance on a sphere (in /jhuapl)
• STRINGAD Convert a RA,DEC string to decimal RA and Dec.
• SUNPOS Compute the RA and Dec of the Sun at a given date
• TEN() Convert sexigesimal number to decimal
• TENV() Like TEN but will work on a vector of sexigesimal numbers. tic positions for contour plots with astronomical labeling.
• UVBYBETA Use Stromgren indices to derive dereddened colors, metallicity, and effective Temperature.
• VACTOAIR Convert vacuum wavelengths to air wavelengths.
• WCSSPH2XY Convert between longitude,latitude to X,Y angular coordinates for 25 different map projection types
• WCSXY2SPH Inverse of WCSSPH2XY
• WCS_DEMO Demo program for WCSSPH2XY and WCSXY2SPH
• WCS_ROTATE Rotate between standard (e.g. celestial) and native coordinates
• XYZ Compute heliocentric rectangular coordinates at given julian date.
• XASTRO Widget interface for precession and coordinate conversion
• YMD2DN() Convert year,month,day to day number of the year (in /jhuapl)
• YDN2MD Convert day number of the year to year, month,day (in /jhuapl)
• ZANG() Compute angular size as a function of redshift in a Friedman cosmology
• ZENPOS Compute the RA and Dec of the local zenith at a given date

• README
• APER Circular APERture photometry
• CNTRD Obtain the centroid of a star in an image array, using FIND algorihtm
• DAOERF Calculate the intensity, (and optionally, the derivatives) of a bivariate Gaussian, integrated over pixels. Called by DAO_VALUE
• DAO_VALUE Obtain the value (and optionally, the derivatives) of a PSF, parameterized as a bivariate Gaussian, and a lookup table of residuals. Called by NSTAR and PKFIT
• FIND FIND point sources within an image
• GETPSF Obtain a PSF (gaussian + residuals) from isolated stars.
• GROUP Place stars with non-overlapping PSF's in distinct groups
• MMM (Mean, Median, Mode) sophisticated sky background computation
• NSTAR Simultaneous PSF fitting of a group of stars
• PKFIT Fit a gaussian + residuals to a isolated star (called by GETPSF)
• RDPSF Read a PSF file that was created by GETPSF into an IDL array.
• RINTER Cubic Interpolation at a set of reference points, optionally obtain derivatives. Called by DAO_VALUE (in /image)
• SKY Compute image sky level using MMM
• SUBSTAR Subtract a scaled PSF at specified star positions
• T_APER Driver procedure for APER with I/O to a disk FITS ASCII table
• T_FIND Driver procedure for FIND with I/O to a disk FITS ASCII table
• T_GROUP Driver procedure for GROUP with I/O to a disk FITS ASCII table
• T_GETPSF Driver procedure for GETPSF with I/O to a disk FITS ASCII table
• T_NSTAR Driver procedure for NSTAR with I/O to a disk FITS ASCII table
• T_SUBSTAR Driver procedure for SUBSTAR with I/O to a disk FITS ASCII table

• README
• DBBUILD Load or append a database with new entry values.
• DBCIRCLE() Find entries within a specified circular area.
• DBCLOSE Close a database
• DBCOMPARE Display the values of two database entries side by side
• DBCREATE Create a new database data, index and/or format file.
• DBDELETE Delete an entry from a database
• DBEDIT Interactively edit the entries in a database
• DBEXT Extract items from a database into IDL variables
• DBFIND() Find entries meeting specified criteria in an IDL database
• DBGET() Use instead of DBFIND when search values are in an IDL vector
• DBHELP List names of databases, or entries within a database
• DBINDEX Update the IDL database index file.
• DBMATCH() Match database entries one-to-one to specified item values
• DBOPEN Open a IDL database
• DBPRINT Print specified fields about specified entries in an IDL database
• DBSORT() Sort entries in an IDL database
• DBUPDATE Update an IDL database with new item values.
• DB_OR() Combine two catalog entry lists, removing duplicate values
• IMDBASE Find all catalog sources within the field of an image (given a FITS header with astrometry)
• DB_ITEM_INFO(),DB_TITLE() Lower level database procedures

• README image slot number. (VMS only)
• IRAFDIR Describe IRAF images on specified directory
• IRAFRD Read a disk IRAF image file into IDL variables.
• IRAFWRT Write IDL image and header to an IRAF (.pix & .imh) file
• MID_RD_IMAGE Read a MIDAS image (.BDF) file into IDL variables
• MID_UP_IMAGE Update the contents of a MIDAS image file
• MID_RD_TABLE Read a MIDAS table (.TBL) file into IDL variables
• MID_UP_TABLE Update the contents of a MIDAS table file.
• MID_RD_DIRDSC Lower level procedure to read MIDAS directory descriptor structure), (VMS only)

• README
• ABSCAL() Apply the BSCALE and BZERO FITS keywords values to a data array
• AD2XY Convert RA and DEC to pixel coordinates X,Y assuming a tangent projection, called by ADXY
• ADXY Interactive version of AD2XY
• CONS_RA() Obtain the X and Y coordinates of a line of constant right ascension
• CONS_DEC() Obtain the X and Y coordinates of a line of constant declination
• EXTAST EXTract ASTrometry parameters from a FITS header into an IDL structure
• FITS_CD_FIX Convert between different representations of the CD matrix
• GET_EQUINOX() Return a numeric equinox value from a FITS header
• GETROT GET ROTation and plate scale from a FITS header
• GSSSEXTAST Extract astrometry parameters from an STScI Survey Image
• GSSSADXY Convert RA, Dec to pixel coordinates for an STScI survey image
• GSSSXYAD Convert pixel coordinates to RA, Dec for an STScI survey image
• GSSS_STDAST Insert the best tangent projection astrometry into an an STScI Guidestar Survey Image
• HASTROM Rotate, Congrid, and/or shift an image until astrometry matches that in a reference FITS header. Used to align images.
• HBOXAVE Boxaverage an image and update astrometry in a FITS header
• HCONGRID CONGRID an image and update astrometry in a FITS header
• HEXTRACT Extract a subimage and update astrometry in a FITS header
• HPRECESS Precess the astrometry in a FITS header to a new equinox.
• HREBIN REBIN an image and update the astrometry in a FITS header
• HREVERSE Reverse an image about either dimension and update astrometry in a FITS header
• HROT Rotate an image and update astrometry in a FITS header.
• MKHDR Make a minimal FITS header for an image array.
• PRECESS_CD Precess coordinate description (CD) matrix in a FITS header to a new equinox. Called by HPRECESS
• PUTAST Put astrometry parameters into a FITS header. If necessary, PUTAST will prompt for the plate scale, rotation, and coordinates and position of a reference star.
• STARAST Obtain an exact astrometry solution given the coordinates and plate position of 2 or 3 stars. Results given as a CD (coordinate description) matrix
• XYAD Interactive version of XY2AD
• XY2AD Convert pixel coordinates X,Y to RA,DEC assuming a tangent projection
• XYXY Convert X,Y values on one image to X,Y values in another image using astrometry in the FITS headers

• README
• ASTRMFIX Update an HST WF/PC or FOC header with rough astrometry
• CONV_STSDAS Convert internal format of .hhd file to that of the host machine architecture. Useful to copy STSDAS files between machines
• EXTGRP Extract group parameter values and place them in a header
• IMGREAD Like STRD but supports group format and tailored to WF/PC, FOC files
• ST_DISKREAD Read an HST FITS file and reconstruct a GEIS (STSDAS) file
• STRD Combine functions of SXOPEN and SXREAD to read STSDAS disk files into IDL data and header variables
• STSUBIM Like STRD but allows reading a subimage
• STWRT Combine functions of SXOPEN and SXWRITE to write IDL data and header variables to STSDAS disk files
• SXGINFO Return info on all group parameters in a FITS header
• SXGPAR() Obtain group parameter values from a FITS header and parameter block
• SXGREAD() Read group parameters from an STSDAS file
• SXHCOPY Copy a selected portion of one header into another
• SXHEDIT Interactively edit a STSDAS header using EDT or the default UNIX editor
• SXHREAD Read a STSDAS header from disk
• SXHWRITE Write a STSDAS header to disk
• SXMAKE Make a basic STSDAS header from an IDL array
• SXOPEN Open an STSDAS (modified FITS) disk header for subsequent I/O
• SXREAD() Read an STSDAS (modified FITS) image from disk
• SXWRITE Write an image to STSDAS (modified FITS) format
• WFPCREAD Read an HST WFPC or FOC STSDAS group image

• README
• FTADDCOL Add a new column to a FITS ASCII table
• FTCREATE Create an empty FITS ASCII table (H and TAB)
• FTDELCOL Delete specified column from a FITS ASCII table
• FTDELROW Delete specified row(s) from a FITS ASCII table
• FTGET() Extract a specified field from a column in a FITS ASCII table
• FTHELP Display the fields in a FITS ASCII table header
• FTHMOD Modify the attributes of a field in a FITS ASCII table
• FTINFO Give information about a specified field in a FITS ASCII table
• FTKEEPROW Subscript (and reorder) a FITS ASCII table
• FTPRINT Print specified columns and rows in a FITS ASCII table
• FTPUT Update or add data to a field in a FITS ASCII table
• FTSIZE Return the size and number of fields in a FITS ASCII table
• FTSORT Sort a table according to the values in a specified field.
• TBDELCOL Delete specified column from a FITS Binary table
• TBDELROW Delete specified row(s) from a FITS Binary table
• TBGET() Extract a specified field from a column in a FITS Binary table
• TBHELP Display the fields in a FITS Binary table header
• TBINFO Give information about a specified field in a FITS Binary table
• TBPRINT Print specified columns and rows in a FITS Binary table
• TBSIZE Return the size and number of fields in a FITS Binary table

FITS Binary Table Extensions I/O

• README
• FXADDPAR Add or modify a parameter in a FITS header array.
• FXBADDCOL Adds a column to a binary table extension.
• FXBCLOSE Close a FITS binary table extension opened for read.
• FXBCOLNUM() Returns a binary table column number.
• FXBCREATE Open a new binary table at the end of a FITS file.
• FXBDIMEN() Returns the dimensions for a column in a FITS binary table.
• FXBFIND Find column keywords in a FITS binary table header.
• FXBFINDLUN() Find logical unit number UNIT in FXBINTABLE common block.
• FXBFINISH Close a FITS binary table extension file opened for write.
• FXBHEADER() Returns the header of an open FITS binary table.
• FXBHELP Prints short description of columns in a FITS binary table.
• FXBHMAKE Create basic FITS binary table extension (BINTABLE) header.
• FXBINTABLE Common block FXBINTABLE used by "FXB" routines.
• FXBISOPEN() Returns true if UNIT points to an open FITS binary table.
• FXBOPEN Open binary table extension in a disk FITS file for reading.
• FXBPARSE Parse the binary table extension header.
• FXBREAD Read a data array from a disk FITS binary table file.
• FXBSTATE() Returns the state of a FITS binary table.
• FXBTDIM() Parse TDIM-like kwywords.
• FXBTFORM Returns information about FITS binary table columns.
• FXBWRITE Write a binary data array to a disk FITS binary table file.
• FXFINDEND Find the end of a FITS file.
• FXHCLEAN Removes required keywords from FITS header.
• FXHMAKE Create a basic FITS header array.
• FXHMODIFY Modify a FITS header in a file on disk.
• FXHREAD Reads a FITS header from an opened disk file.
• FXPAR() Obtain the value of a parameter in a FITS header.
• FXPARPOS() Finds position to insert record into FITS header.
• FXREAD Read basic FITS files.
• FXWRITE Write a disk FITS file.

FITS I/O

• README
• CHECK_FITS Check that the NAXISi and BITPIX keywords of a FITS header (or STSDAS header) agree with a supplied array
• FITSDIR Display info about primary FITS header(s) on disk
• FITSRGB_to_TIFF Combine separate red, green, blue FITS files into TIFF format
• FITS_INFO Display info about disk FITS file(s) at a terminal or in Common
• FXPOSIT() Open a FITS file positioned to beginning of a specified extension
• HEADFITS() Read a FITS header from a disk FITS file.
• MKHDR Make a minimal FITS header for an image array.
• MODFITS Modify the header or data in a FITS array (without changing the size)
• MRDFITS() Read FITS file mapping table columns into IDL structure tags
• MRD_HREAD Like FXHREAD but can also read a FITS header from a Unix pipe
• RDFITS_STRUCT Read an entire disk FITS file into an IDL structure
• READFITS() Read a disk FITS file into an IDL data and header array.
• SXADDHIST Add a history record to a FITS or STSDAS header
• SXADDPAR Add or modify a parameter in a FITS or STSDAS header
• SXDELPAR Delete a keyword from a FITS or STSDAS header
• SXPAR() Obtain the value of a keyword in a FITS or STSDAS header
• WRITEFITS Write IDL data and header array to a disk FITS file.

Image Manipulation

• README
• BOXAVE() Boxave an image, always using at least REAL*4 arithmetic
• CONVOLVE() Convolve an image with a PSF using the product of Fourier Transforms
• CORREL_IMAGES() Correlation of two images. Called by CORREL_OPTIMIZE
• CORREL_OPTIMIZE Compute the optimal pixel offset of one image relative to another by maximizing the correlation function.
• CORRMAT_ANALYZE Analyze the correlation function made by CORREL_IMAGE
• DIST_CIRCLE Create an array where each pixel value is equal to its distance to a specified center. Useful for circular aperture photometry.
• DIST_ELLIPSE Create a mask array useful for elliptical aperture photmetry.
• FILTER_IMAGE() Like MEDIAN or SMOOTH but handles edges & allows iteration
• IMLIST Display image pixel values around a specified center
• MAX_ENTROPY Deconvolution by Maximum Entropy, given a PSF
• MAX_LIKELIHOOD Deconvolution by maxmimum likelihood, given a PSF
• MEDARR Median filter across a set of images (e.g. for cosmic ray removal)
• PSF_GAUSSIAN() Create a 1-d, 2-d, or 3-d Gaussian with specified FWHM, center
• SIGMA_FILTER() Replaces pixels deviant by more than a specified sigma from its neighbors. Useful for cosmic ray removal.

Math and Statistics

• README
• AVG() Return the average value of an array or 1 dimension of an array.
• FACTOR Find the prime factors of a given number (in /jhuapl)
• FITEXY Best straight-line fit to data with errors in both coordinates
• FLEGENDRE() Compute the first M terms in a Legendre polynomial expansion
• GAUSSIAN() Evaluate a 1-d gaussian and optionally its derivative
• HERMITE() Interpolate a tabulated function using a Hermite spline
• KSONE Compute the one-sided Kolmogoroff-Smirnov statistic
• KSTWO Compute the two-sided Kolmogoroff-Smirnov statistic
• LINTERP Linearly interpolate X,Y vectors onto a new X grid (e.g. interpolate wavelength-flux vectors onto a new wavelength grid.)
• MINF_BRACKET Find 3 points which bracket the minimum of a function
• MINF_PARABOLIC Minimize a function using Brent's method with parabolic interpolation
• MINF_CONJ_GRAD Find local minimum of a scalar valued function of several variables using conjugate gradient method
• PCA Perform a principal component analysis (Karhunen-Loeve expansion)
• PENT() Return the information entropy S of time-series data for a set of trial periods
• POIDEV() Generate a Poisson random deviate
• POLINT Polynomial interpolation of an (X,Y) pair
• POLYLEG() Evaluate a Legendre polynomial with specified coefficients
• POLY_SMOOTH() Apply a least-squares (Savitzky-Golay) polynomial smoothing filter
• PROB_KS Return the significance of a Kolmogoroff-Smirnov statistic
• RANDOMP Create a vector of random numbers distributed as a power-law
• QSIMP Integrate using Simpson's rule to specified accuracy
• QTRAP Integrate using trapezoidal rule to specified accuracy.
• QUADTERP Quadratic interpolation of X,Y vectors onto a new X grid
• SIXLIN Compute linear regression by 6 different methods.
• SPLINE_SMOOTH Compute cubic smoothing spline to (weighted) data
• TABINV Find the effective index of a function value.
• TRAPZD Compute Nth iteration of trapezoidal rule. Called by QSIMP, QTRAP
• TSUM() Trapezoidal integration of the area under a curve
• ZBRENT() Find the root of a function known to lie between specified limits

Plotting Procedures

• README
• CLEANPLOT Reset all plotting system variables to their default (X) values
• CURFULL Like intrinsic CURSOR procedure but with a full-screen cursor
• LEGEND Create an annotation legend for a plot
• LEGENDTEST Demo program demonstrating the capabilities of LEGEND
• LINEID_PLOT Annotate the identified lines in a spectrum
• MULTIPLOT Create multiple plots with shared axes
• OPLOTERR Overplot Y vs. X with optional X and Y error bars
• PLOTERR Plot Y vs. X with optional X and Y error bars
• PLOTHIST Plot the histogram of an array
• PLOTSYM Define useful plotting symbols not in the standard PSYM definition
• PARTVELVEC Plot the velocity vectors of a set of particles

IDL Structure procedures

• README
• COPY_STRUCT Copy Fields with matching Tag names from one structure to another
• COMPARE_STRUCT() Compare all matching Tag names and return differences
• CREATE_STRUCT Create an IDL structure from a list of tag types and dimensions
• MRD_STRUCT() Like CREATE_STRUCT but tag values can be specified in a string
• N_STRUCT() Return number of elements in a structure array and number of tags
• PRINT_STRUCT Print specified tags from structure (to LUN if given)
• SIZE_STRUCT() Obtain the size in bytes of an IDL structure definition
• TAG_EXIST() Determine if a tag exists in a given structure
• WHERE_TAG() Like WHERE but works on a structure with a variable tag name

STSDAS (Binary) Table I/O

• README
• TABLE_APPEND Append a list of STSDAS tables to create a single table.
• TABLE_CALC Add a new table column from an expression using existng columns.
• TABLE_CONV Convert an STSDAS table into the host machine architecture
• TABLE_DELETE Delete specified rows from an STSDAS table
• TABLE_EXT Extract column(s) of data from an STSDAS table to IDL variable(s)
• TABLE_HELP Describe an STSDAS table.
• TABLE_LIST List the contents of an STSDAS table
• TABLE_PRINT Print a disk STSDAS table in tabular form
• TABLE_SORT Order the contents of an STSDAS table by the specified column
• TAB_ADDCOL Add a new column to a STSDAS table
• TAB_COL Extract column info from a table control block. Called by TAB_READ
• TAB_CREATE Create an empty STSDAS table on disk
• TAB_DEL Delete specified row(s) from an STSDAS table
• TAB_EXPAND Expand the size of an STSDAS table. Called by TABLE_APPEND
• TAB_FORTOSPP Convert a FORTRAN print format to SPP. Called by TAB_MODCOL
• TAB_MODCOL Modify a column name, format or units in an STSDAS table.
• TAB_NULL() Locate null values in a STSDAS table. Called by TAB_PUT
• TAB_NULLROW Place null values into a STSDAS table. Called by TAB_PUT
• TAB_PRINT Print the contents of an STSDAS table in tabular form
• TAB_PUT Put new values into a column of an STSDAS table
• TAB_READ Read table control block and data array from a disk STSDAS table.
• TAB_SIZE Return the size of a STSDAS table. Called by TABLE_LIST
• TAB_SORT Sort a STSDAS table according to the specified column
• TAB_SPPTOFOR Convert SPP print format to FORTRAN. Called by TAB_PRINT
• TAB_TO_DB Convert an STSDAS table to an IDL database
• TAB_VAL() Extract values from a single column of an STSDAS table
• TAB_WRITE Write a STSDAS table to a disk file

Tape IO Procedures (Unix and VMS only)

• README
• CHECK_TAPE_DRV Associate a unit number with a Unix tape drive
• DISMOUNT Unix emulation of VMS DISMOUNT command
• FITSLIST List the headers on a FITS tape.
• FITSTAPE() Lower-level function to perform FITS tape I/O.
• FXTAPEWRITE Copy a disk FITS file to tape
• FXTAPEREAD Copy a FITS file from tape to disk
• FXTPIO_READ Reads a file from a tape--called from FXTAPEREAD.
• FXTPIO_WRITE Writes a file to a tape--called from FXTAPEWRITE.
• REWIND Unix emulation of intrinsic IDL VMS REWIND command
• SKIPF Unix emulation of intrinsic IDL VMS SKIPF command
• TAPRD Unix emulation of intrinsic IDL VMS TAPRD command
• TAPWRT Unix emulation of intrinsic IDL VMS TAPWRT command
• WEOF Unix emulation of intrinsic IDL VMS WEOF command
• TINIT Position a tape between final double EOF for appending new files

TV Display Procedures

• README
• BLINK Blink two or more windows in an image display
• CURS Change the shape of the (X windows only) cursor
• CURVAL Interactive display of image intensities and astronomical coordinates
• PIXCOLOR Set specified pixel values to a specified color
• SIGRANGE() Find range of pixel values which contain 90% of the image values
• TVBOX Draw a box of specified size on the image display
• TVCIRCLE Draw a circle of specified radius on the image display
• TVELLIPSE Draw an ellipse of specified axes on the image display
• TVLASER Write an image to postscript file with annotation from a FITS header
• TVLIST Display intensity values surrounding the cursor position
• UNZOOM_XY Convert from window coordinates to image coordinates
• ZOOM_XY Convert from image coordinates to window coordinates

Miscellaneous (Non-Astronomy) Procedures

• README
• ASTROLIB Add the non-standard system variables used in the IDL Astronomy User's Library
• BOOST_ARRAY Append one array onto another, adjusting dimensions if necessary
• BREAK_PATH() break up a !PATH-like string into individual directories
• BSORT() Like the IDL SORT function but subscript order is maintained when value are equal -- like a bubble sort.
• CIRRANGE Force an angle to be in the range 0 to 360 (or 0 to 2*!PI).
• CONCAT_DIR concatenate directory and file name for current OS
• CONV_UNIX_VAX Convert IEEE datatype to VMS datatypes
• CONV_VAX_UNIX() Convert VMS datatypes to Unix using proper byteswapping
• DATATYPE() Return the datatype of an IDL variable as a string (in /jhuapl)
• DELVARX Delete an IDL variable; like DELVAR but works at any calling level
• DETABIFY() Replace tabs in a character string by equivalent number of spaces
• F_FORMAT() Find the "best" F format to display an array of REAL*4 numbers.
• FDECOMP Decompose a file name (Disk + Directory + Name + Extension + Version)
• FINDPRO Find all occurences of a procedure in one's !PATH
• FIND_WITH_DEF Search for files with default path and extension
• FORPRINT Print a set of vectors by looping over each index value
• GETFILES Interactively specify a list of file numbers.
• GETLOG() Format the input name as a logical directory in the host OS
• GETOPT() Parse a user supplied string into numeric value(s).
• GETPRO Search !PATH directory for a procedure and copy into user's directory
• GETTOK() Extract a string up to a specified character.
• GETWRD() Get specified item (word) from a string (in /jhuapl)
• HOST_TO_IEEE Convert IDL variable from host machine bit order to IEEE
• HPRINT Pretty terminal display of a FITS header (or other string array)
• IEEE_TO_HOST Convert IDL variable from IEEE bit order to host machine
• ISARRAY() Determine if an IDL variable is an array (in /jhuapl)
• IS_IEEE_BIG() Determine if the host machine is IEEE big endian
• LIST_WITH_PATH() Search for files within specified directory path
• MAKE_2D Change from 1-D indexing to 2-D indexing
• MATCH Find the subscripts where the values of two vectors match.
• MRD_SKIP Skip a number of bytes from current location in a file or a Unix pipe
• MINMAX() Return the min and max of an array in an 2 element vector
• NINT() Like intrinsic ROUND() function but returns integer instead of long
• NULLTRIM() Delete all characters after, and including, the the first null byte(0). Called by TAB_PUT.
• NUMLINES() Return the number of lines in a file
• ONE_ARROW Draw an arrow labeled with a single character
• ONE_RAY Draw a ray by specifying starting point, angle, and length
• ORDINAL() Return the English equivalent of ordinal numbers, i.e. '1st','2nd'
• OSFCNVRT() Format the input as a logical name in the host operating system
• OS_FAMILY() Return the operating system formatted as in !VERSION.OS_FAMILY
• POLREC Convert from polar to rectangular coordinates (in /jhuapl)
• PRODUCT() Return the product of all the elements of an array.
• QGET_STRING() Read a string (eg. password) from the keyboad without echoing it
• RDFLOAT Quickly read an ASCII file with columns of data into IDL vectors
• READCOL Read a file of free-format ASCII data into IDL vectors
• READFMT Quickly read a file of fixed-format ASCII data into IDL vectors
• READ_KEY() Like GET_KBRD but returns a code for escape sequences.
• RECPOL Convert from rectangular to polar coordinates (in /jhuapl)
• REMCHAR Remove all appearances of a character from a string.
• REM_DUP() Remove duplicate values from a vector.
• REMOVE Contract a vector or up to 8 vectors by removing specified elements.
• REPCHR() Replace all occurrences of one character by another (in /jhuapl)
• REPSTR() Replace all occurrences of one substring in a string by another.
• SCREEN_SELECT Allow user to interactively select from a list of strings Used by the database software
• SELECT_O VT100 terminal branch of SCREEN_SELECT
• SELECT_W IDL widget branch of SCREEN_SELECT.
• SPEC_DIR() Complete specification of a file name using default disk & directory
• STORE_ARRAY Insert one array into another, adjusting dimensions if necessary
• STREBCASC() Convert an EBCDIC string scalar or vector to its ASCII equivalent
• STRN() Convert a number to a string and remove padded blanks.
• STRNUMBER() Determine whether a string is a valid numeric value.
• TEXTOPEN Open a file for text output as specified by !TEXTOUT Controls the print output device for many procedures.
• TEXTCLOSE Close a file that had been opened by TEXTOPEN.
• TO_HEX() Translate a decimal integer to a hex string. Called by AIPSNAME.
• VALID_NUM() Determine if a string is a valid number (cf. STRNUMBER)
• VECT() Display a set of numbers to a string with delimiters
• WHERENAN() Find points equal to IEEE NaN (not a number) values
• ZPARCHECK Check the type and size of a parameter