IFEFFIT is an interactive program for XAFS Data Analysis. It runs like a command-line 'shell', in which you enter commands to process and manipulate data. IFEFFIT has a fairly high-level command language so that you can do the complex manipulation needed for XAFS analysis (such as background subtraction and Fourier transforms) with simple commands.
One of the principle features of IFEFFIT is that it's command-line functionality can be run in either interactively, from files of commands (i.e., batch files), or accessed from within other programming and high-level scripting languages like Tcl, Perl, and Python. While the full details of this are beyond the scope of this tutorial, you may find it useful to keep in mind that IFEFFIT is not just a single program, but a family of related programs and libraries. This tutorial gives a brief description of the IFEFFIT command structure and syntax, and an overview of the main IFEFFIT command-line program. Other documentation is available at the IFEFFIT web site: http://cars9.uchicago.edu/ifeffit/
I should also mention that the program G.I.FEFFIT, a graphical-user-interface for IFEFFIT, acts as an ``enhanced shell program'', so that almost everything presented in this tutorial will also work for G.I.FEFFIT. At this writing, G.I.FEFFIT is still incomplete but functional and under development.
Once IFEFFIT has been installed on your computer, typing ifeffit at the system command prompt will start the basic IFEFFIT program. You should get a set of messages and a command prompt that looks something like this:
Ifeffit 1.0053 Copyright (c) 2001 Matt Newville, Univ of Chicago Ifeffit shell version 1.0e with GNU Readline Ifeffit>At this point, you're ready to start typing IFEFFIT commands at the prompt. Try typing
Ifeffit> print "1+1 =",1+1If the result makes sense to you, you're ready to continue. Now that you've started IFEFFIT successfully, the rest of this tutorial describes what to type. One particularly useful IFEFFIT command is quit, which will exit IFEFFIT.
The main IFEFFIT program has a friendly shell environment and allows a simple subset of system-level commands to be executed from within the command-line program. On Unix systems, the commands ls and more will give a directory listing and show the contents of a file, respectively. On Windows, the command dir takes the place of ls. Typing help will give a brief list of the most common commands, while help <command_name> will give a little more of information on the nature and use of the selected command. The command history buffer is accessible through the up- and down-arrow keys, so that you can scroll through and edit previously executed commands. Further information about the command-line program on Unix systems is given in section 10.