Introduction to IDL. R. W. O'Connell Contents Translations Section I of this Guide is for those who are unfamiliar with IDL or who are trying to decide whether to adopt it. Sections II and III are for users. Although the examples are taken from applications in astronomy, most of the Guide is general enough to be useful to workers in medical imaging, geophysics, or other areas for which IDL is well suited. 1. [Up to Contents] The Interactive Data Language (IDL) is a proprietary software system distributed by Exelis Visual Information Solutions, Inc.
IDL is currently available in LINUX, UNIX/Solaris, Windows, and Macintosh versions. IDL is not simply a package of task-oriented routines in the style of astronomical software systems such as IRAF or CIAO. Interactivity, graphics display, and array-oriented operation. Users who are conversant with FORTRAN, C, C++, or other high level languages will have little trouble understanding IDL. 2. 3. IDL is ideally suited for software exchange over the Web. 5. IDL Astronomy User's Library. IDL Data Visualization Solutions. IDL Curve Fitting and Function Optimization. MPFIT - Robust non-linear least squares curve fitting These IDL routines provide a robust and relatively fast way to perform least-squares curve and surface fitting. The algorithms are translated from MINPACK-1, which is a rugged minimization routine found on Netlib, and distributed with permission. This algorithm is more desirable than CURVEFIT because it is generally more stable and less likely to crash than the brute-force approach taken by CURVEFIT, which is based upon Numerical Recipes.
MPFIT has additional capabilities not found in CURVEFIT. Model parameters can be "frozen" (that is, held constant during the fitting process). Simple boundary constraints can be imposed on parameter values, which can be helpful to keep parameters from becoming negative, for example. You can cite MPFIT in your papers! A C version of the library is available! NEW! Frequently Asked Questions There are several files included in the MPFIT package. Likelihoods - Alternate likelihood functions. Image Display with IDL. Image Display with IDL IDL provides many tools for displaying, modifying and analyzing images. The topics in this section are meant to get you started with a basic set of tools. We will enlarge this toolbox as we go along in the course. The topics of this section are: Reading Image Data [TOP] Image data can be read from files in several formats.
IDL> Read_png,'C:\myimages\scene.png',image IDL provides routines of the form Read_xxx to read a number of image formats. Beginning with version 5.3, IDL provides a generic image-reading routine called READ_IMAGE. I find it handy to use the Dialog_Pickfile function to help me pick the full name of the image file. IDL> fname=Dialog_Pickfile(FILTER='*.png') IDL> ok=Query_Image(fname,info) The variable OK will equal 1 if the image file can be read and 0 if it cannot be read. the variable INFO is a structure that contains information about the image in the file. IDL> Help,info,/STRUCTURE Suppose that we had picked the file fname='peppers.png'. Documentation of IDL Functions.