Overview

IGOR Pro from WaveMetrics, Inc., is an integrated program for visualizing, analyzing, transforming, and presenting scientific data. Originally developed for the Macintosh, Igor has recently been released for Windows 95 and NT with a virtually identical user interface and feature set. Igor can import data from a wide variety of sources; additionally, users can create custom data-loading routines. Among Igor's many analysis features are tools for curve-fitting and -smoothing, Fourier transform, waveform arithmetic, and image-analysis operations. Igor also offers a powerful, interactive C-like programming environment for rapid development of macro procedures.

The program's organization, documentation capabilities, and data management have been carefully designed to aid users in analyzing and annotating complex experiments. Data, graphs, tables, notebooks, and page layouts for one experiment are automatically stored in a single file, and experiment-specific window-creation commands are executed upon reopening an experiment file. Igor's interface is highly customizable via user-created dialog boxes and control panels. Scientific graphs are easily created in publication-ready format without the need for touch-up in a drawing program. Although some users might find Igor's power and complexity somewhat daunting, this is offset by a well-written manual and online help system, as well as by WaveMetrics' excellent customer support.

Available platforms	Windows 95 or higher, Windows NT 4.0 or higher, or Macintosh System 7.0 or higher
System requirements	Macintosh CD-ROM for installation. 68020 processor running System 7 or higher, with minimum 8 Mb program memory allocation. A math coprocessor or PowerPC processor is required for the Graphical Slicer and Surface Plotter XOPs. Windows CD-ROM for installation. PC capable of running Windows 95 or NT 4.0 or higher, with at least 32 Mb of system memory. Monitor of at least 640 x 480 pixels displaying at least 256 colors.
Test platforms	Power Macintosh with 603e/200-MHz CPU, System 8.1, and 16 Mb dedicated program memory. Also tested on a Dell PC with a Pentium 166-MHz CPU, Windows 95, and 96 Mb of system memory.
Price	$450 commercial, $340 academic, $85 student

How Long Did It Take to Learn to Use It Productively?

A minimum of several weeks of dedicated use.

Product Quality

Customizability

Excellent.

Ability to Program in Scripts, Add Extension Modules, etc.

Programming using Igor Pro's built-in C-like language adds detailed control of objects and scripted/recorded actions, and includes data storage elements (variables, strings, and waves), assignment statements, flow control (conditionals and looping), built-in and external operations and functions, and the ability to define and call subroutines. User-written functions are compiled and, therefore, execute very quickly. Writing, compiling, and testing of functions is smoothly interactive. Overall, Igor's programming functions are sophisticated, robust, and extremely capable; there's very little that can't be customized and controlled via its programming language.

Ability to Import and Export in Different File Formats

Data are typically acquired from some type of scientific instrument and imported from a file. Supported file formats include binary, text, AIFF, Excel, FITS, HDF, JCAMP, MatLab, Nicolet, PICT, TIFF, and Sun Raster, and custom data-importing routines can be written for almost any other file type. WaveMetrics also offers an optional NIDAQ Tools module that can be used to acquire waves directly from National Instruments boards. Igor can even create a scrolling virtual chart recorder for data acquisition and display, although this is a relatively complex exercise requiring substantial programming effort. Graphs may be exported in normal, expanded, and high-resolution PICT formats (Macintosh), EMF, WMF, and BMP formats (Windows), or PNG and EPS formats (both platforms). The manual discusses why most graphics file formats do not exchange universally and transparently with optimal resolution between programs on each platform (not to mention between the two platforms), and gives helpful suggestions for troubleshooting this larger-than-Igor problem.

Useful or Unusual Features

Figure 1

True to its scientific roots, Igor's user interface is relatively spartan (figure 1). There are no toolbars, Macintosh three-dimensional window elements are absent or minimal, and the use of color is strictly functional. Program control is via a unique combination of graphical and command-line interfaces; in most cases, either input method may be used to execute a particular function. As menu commands and window buttons are used in the graphical interface, command-line equivalents are generated and displayed in the command window, which also records the history of the work session. Simple macro procedures can be built using commands copied from the work-session history, similar to shell scripting in Unix.

Figure 2

A very useful feature of Igor is that it can dynamically explore graphed data while maintaining a well-formatted layout. For example, users can specify an approximate number of ticks for each axis and the program will keep close to these specifications over a wide range of rescaled or zoomed window sizes. Re-dimensioning a graph results in other intelligent changes: font sizes of axis labels are optimized for the altered graph size, and tick marks and labels are reduced in density so as not to overcrowd themselves if the graph is made smaller. Click-dragging in part of the graph creates a selection area that can be zoomed in or out using several different scaling options (figure 2). Data within zoomed-in areas can be panned by holding an option key down while dragging with the mouse; the x- and y-axis values are updated accordingly. Igor's drawing tools allow user-created objects or text to be anchored and scaled proportionately with the graph as it is resized, although zooming the graph may require some manual adjustments of the anchored objects afterward. Igor even automatically updates axis labels when appropriate - for example, changing "milliseconds" to "microseconds" after zooming in. If you spend a lot of time fine-tuning graphs, you'll greatly appreciate WaveMetrics' attention to these details.

Figure 3

User-created procedures can be added to Igor's menus or linked to buttons on custom control panels so that they can be invoked via the program's graphical interface (figure 3). This means that the person performing the analysis needn't be concerned with the hairy command-line details, and can analyze data without having to learn Igor commands. Bearing this in mind, it might prove cost-effective to hire someone with moderately good programming skills to create an easy-to-use graphical front end for your Igor analysis procedures.

Limitations

Igor has very few specific limitations, and those encountered were very minor. Its biggest drawback is that you have to write programming procedures to do detailed data analysis, although graphing can be done easily without any programming. Note that it may not actually be necessary to write analysis procedures from scratch; the Igor user contributions site has dozens of user-created Igor procedures available for downloading and is worth checking to see if you can find something suited to your needs.

Comparisons with Similar Software

Not applicable.

Technical Support and Documentation

Figure 4

Support and documentation for the program are excellent. WaveMetrics is highly attentive to users' comments and suggestions; bugs are quickly addressed and fixed, sometimes within hours of an initial report. In addition to Igor's on-line help system (figure 4), the Macintosh version has balloon help and the Windows version features tool tips, status line help, and context-sensitive help. The manual is comprehensive and well written. It provides useful examples, detailed references, and answers to common questions, and is notably candid in discussing the program's known limitations. Since these aids are supplemented by WaveMetrics' e-mail technical support and Igor's Internet mailing list, an impressive array of documentation, assistance, and expertise is available. WaveMetrics also has a toll number for technical support during business hours, Pacific Standard Time. In my experience WaveMetrics' support was polite, helpful, and readily matched the level of effort expended to learn the program.