Frequently Asked Questions About SysQuake

Q: What's the graphic in the splash box?
A: The logo of SysQuake contains a part of the root locus of a sixth-order system whose coefficients are contained in an ellipsoid. The sixth-order controller is chosen for esthetics reasons. The shades of gray correspond to different sizes of ellipsoids. The root locus was created with the SQ file iupp.sq.
Q: Can I use SysQuake to replace other numerical computation software?
A: SysQuake is designed for interaction. However, its language, LME, can be used for any kind of computation. There are two recommended ways to develop your application. First, you can write new libraries (.lml files) and call their functions from the command-line interface, which permits you to use variables to store intermediate results. You have access to graphics, file input/output, extensions, etc. Second, you can write commands in an SQ script, which has two advantages: execution starts automatically when you open the file in SysQuake, and you can change the scale of graphics (SysQuake runs the whole script again to draw scale-dependent graphics in an optimal way).
Q: What is _settingFlags?
A: Options for the entries of the Settings menu, which are specified by _enable and _checkmark, are grouped together into a function named _settingFlags. If an error occurs during the evaluation of one of the expressions, it is likely to be reported with a reference to _settingFlags. The line number corresponds to the number of the menu entry.
Q: On the Macintosh, the screen blinks when I manipulate a graphic. Is it normal?
A: When it has enough memory, SysQuake uses an internal representation of the content of the window to draw the figures, and then copies it to the screen. This prevents the blinking you can see, which results from erasing the window before drawing an updated figure. On the Macintosh, to give more memory to SysQuake, make sure that it is not open, select its icon in the Finder (single-click it), then choose Get Info in the File menu. You can increase the Preferred Size. A value of 10000 KB (about 10 megabytes) should be enough even for a large window and millions of colors. If you do not see the field "Preferred Size" and you have Mac OS 8.5, select Memory in the popup menu in the Info window. If you cannot edit the size, SysQuake is probably running, or the disk is locked. SysQuake may also support temporary memory, which adds some flexibility by using memory not used by Mac OS. See Getting Started for more details.
Q: Why does the frequency response disappear at negative frequencies when a large part of positive is displayed?
A: Because of the symmetry, frequency responses are usually displayed only for positive frequencies. SysQuake leaves a small margin between zero and the left of the figure. To avoid displaying a peak at low frequency when the frequency scale is linear, which might be seen as a resonance, negative frequencies are displayed only when they represent more than 10 % of the total range.
Q: Why is SysQuake for Windows much larger than SysQuake for Macintosh?
A: While a large part of SysQuake is based on the same source code for Macintosh and Windows computers, which ensures a very high level of cross-platform compatibility, simplifies the tests and improves the quality of both versions, the graphical user interface and the access to the operating system is platform-dependent. On the Macintosh, this part, written in C, is based directly on Mac OS calls, which permits efficient coding. On Windows, it is based on a C++ framework, which simplifies the source code by a large amount (user interface elements such as toolbars or the mechanism to dispatch user actions are provided almost without coding), but needs a large library. While it would be possible to include this code as a shared library (DLL), it is safer to include it in SysQuake itself to avoid problems when the operating system is updated or other programs are installed. In addition, the installation process is as simple as dragging SysQuake or its directory from a cd-rom to your hard disk, and the uninstallation process as simple as dragging it to the Recycle Bin.

Copyright 1998-2001, Calerga.

All rights reserved.