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Xact v5.0- by Martin R. Hadam


Scientific Graphing and More

The latest version of the scientific graphing software Xact has just been released. It greatly expands functionality compared to its predecessor and sets new standards in both ease of use and speed. At this time, only a German version is available from SciLab (Hamburg, Germany) but an English version (including a fully translated manual) is definitely in the works and due for release in the not too distant future. A demo version is also to be made available on May 20th.

Xact has its roots in the Atari platform and this is most strikingly reflected in its low resource consumptions: a 2.2MB exe does it all; no program-specific DLLs (except for two small ones to enable drag and drop functionality for the Xact objects) since all graphic functions are made to work via system calls. Compare this to the competition on Windows machines and you'll be happily surprised. But despite the fact that you only get three diskettes (including samples), Xact is by no means lightweight. (By the way, for those who really depend on Windows, there are also 16- and 32-Bit Windows versions available.)

Xact comes with two types of windows: table and graph windows. Also, you can have as many windows as you like, which is very useful. One of the program's most impressive features is the consistent use of context menus. They are really context sensitive, they contain only valid entries and, in version 5.0, they have been deliberately kept short to avoid long mouse paths. Even the default entries change according to the most likely choice in a given context. This feature makes Xact a pleasure to work with for both the novice and the experienced user.

Being a longtime Xact addict, I often find myself clicking on the right mouse button in many other programs with little benefit. Also, many keyboard shortcuts have been implemented, especially for the graphic functions since combining mouse and keyboard often speeds up work considerably.

The table window has been greatly overhauled in this version of Xact. Users can now introduce links to other tables (including non-Xact tables) and format tables in a manner similar to spreadsheets with different lettering and multiple rows per field. This comes in handy when using the much enhanced table function (GIF, 7.4k) in the graph display. The transform functions have been enhanced and some basic statistical features have been included. Note that you can also use date and time as a parameter in tables with highly sophisticated formatting options (also to be reflected in the resulting graphs). Also, Xact now includes a digitizing function which allows for creating a data table by entering data graphically (either from scanned figures or using a pen).

Creating a graph from your data is as simple as defining both axes (or multiple ones), choosing error bars (error bars can now extend also along the x- axis), and selecting from eleven basic graph types (bar, line, contour etc.). Each basic graph type is further detailed as a selection of three to sixteen more prototype graphs with quite a few additional options where appropriate. In total, there are 83 different prototypes to choose from.

New types are Fourier-analysis (GIF, 6.7k), bitmap plots (GIF, 17.6k) and much enhanced contour plots (GIF, 22.5 k).

Since contour plots of flow cytometric data are quite important for my own work as an immunologist, it is of note that Xact can now also set contours according to probability (GIF, 14.6k). This is a hard to-find feature elsewhere.

Clicking on a prototype graph icon will immediately create a graph in a new window or, when selected, add it into any other graph window on the screen. Each graph is linked by default to its data set to allow for easy updating. There is also a shortcut to graph creation by using template graphs, which in turn can be generated from any existing graph. Templates are easy to choose from due to the Xact file menu with large preview thumbnails. By using a template, you can also indicate which parts of the data should be used to make the graph.

Once a graph is created, you may want to embellish it to your liking. Resizing an entire graph will also adjust line thickness, font size and symbols. Whenever you right click on any part of a graph object, you will notice the appropriate options in the context menu. For example, assume you have a line diagram with two lines, one of which you want to change to bars. To accomplish this is easy; you would just right-click on the one you want to change and select "graphstyle" which would allow the conversion of only this part (GIF, 10k) into either a bar, line or step graph.

But there is even more possible with Xact: selecting "extras" will allow for overlaying a curve fit (GIF, 11.6k) or doing regression analysis; you can select from a host of options for Fourier analysis, or you can output those values to create a new table. This is neat when you receive a graph from a colleague, but you can still go to the actual numerical values. And if you think your measurements don't fit reality, you can use "move points" to create a new data set containing values which fit your ideas best.

On the same line, you can introduce changes to axes, symbols, lines, fills and legends by clicking with the right mouse button on the appropriate item. Also note that you can set line style to have either sharp or rounded edges (GIF, 4.6k).

The new cursor types also come in handy. The cursor will change shape depending on whether it is located above objects, edges of objects or corners. Also, when you move or resize objects, the cursor shape will guide you to readily position your objects with single pixel accuracy. Finally, there is an alignment tool which assists in positioning objects.

If you happen to deal with bar graphs you will definitely love the new fill type editor. It will let you do almost anything you could think of to make a fill pattern out of two lines. It is particularly useful if you want to fine-tune a black-and-white graph or for optimal display of pie graphs (GIF, 6.4k).

Of course, since all parts of a graph are objects as well, you can substitute bars by dropping other graphs onto them -- you can even replace symbols with your company logo if you like. This is most readily done from the Xact symbol folders, which contains a collection of useful premade graphs.

Each graph object can now be positioned, sized, arranged and layered in depth from the context menu; as well as being set to locked, hidden or reference (helper) object. It is also possible to assign a unique name to each individual graph object. While this may appear unusual at this point, read on until we touch Xact's automation features. You can also set a graph to extend over the entire paper format. This is most useful when defining a colored background for a slide. Choose a rectangle with your desired colors and set it to "background" and "entire screen" and you're done. If you put such an object into a symbol folder, you simply drag your personal background to the screen.

Graphic output is done in a variety of formats; here, in case we don't print it directly we mostly use the postscript option. Note, that you can create a graph directly in "slide" format which is different from standard paper sizes. All in all, we use Xact to create any type of graphic (bitmaps exempted, of course) -- e.g. illustrations like chromosomes (GIF, 2.2k), molecular models, schemes for overheads, or slides containing bitmaps (GIF, 7.9k), not just graphs containing numerical data. (Please note that the samples shown have been generated at true color and secondarily reduced to 256 colors.)

What else is left? Printing of graphs is via drag and drop and is very fast due to metafile spooling. You can change data links at any time and have your graph recalculated with new data. You can issue REXX macros from within Xact (this is old news) and from the command line using the novel Xactrexx.dll. This dll allows you to invoke Xact from a cmd file and provides you with access to almost any table and graph setting available from the GUI. I've recently used it to create a 50,000 cell Xact table from a series of HTML files containing scientific data. I've never seen such smooth operation on my Warp Server SMP machine: two processors at close to constant 70% load for about 10 minutes. And while that table was being created, I could already scroll through it!

Using the object names mentioned above, you can now even manipulate individual graph objects using REXX! Imagine the possibilities when you're using REXX to query a database and have the results displayed in Xact. But it does not stop there. Using the XrGPollObj function from Xactrexx, you can detect which object was clicked on in your graph and use this object name to introduce choices in your database query. So you can create truly interactive systems using Xact and REXX. (By the way, using the available C interface, you can accomplish the same thing.)

Conclusions

In summary, Xact matches featurewise any other program I've come across in its area. There are minor differences, but they don't really matter much. Xact is also a superb general purpose vector graphics program. Where Xact is clearly ahead of the pack is usability and speed -- and its automation is a class of its own.

My wish list? I would like to have some (not all!) commands voice activated. So by saying "zoom" the area under the cursor would be zoomed... etc. That would be neat.


 * Xact v5.0
by SciLab GmbH
Isestrasse 57 D-20149
Hamburg Germany Fax: (+49) 40 479 344
MSRP: DM 795
Dr. Martin R. Hadam is in the Department of Pediatrics at the Medical School in Hannover, Germany. His research focusses on inborn errors of the immune system. He has been an avid user of OS/2 since v2.0 and longtime beta tester of Xact.

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