Frequently Asked Questions About Sysquake

Q: What's the graphics 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: 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.