On 02.11.2009, at 00:27, Luca Favatella wrote: > On 31/10/2009, Lukas Reichlin <[email protected]> wrote: >> Ciao Luca >> >> When you create static gains (e. g. sys = tf (12) or sys = ss (17)) >> with control-oo, sampling time is set to -1, which means >> "unspecified". This way, you can connect them conveniently with other >> systems (e.g. sys2 = tf (1, [1, 1]) or sys3 = ss (-1, 1, 1, 0, 0.1)), >> which are either continuous or discrete. > > I added some test cases (svn r6425) with these your examples. >
Good. > [...] > >> Stable poles have real parts < 0 (continuous) or are within the unit >> circle (discrete). When you set tol greater than zero, barely stable >> poles (possibly due to numerical "noise") are regarded as unstable as >> well. > > Ok, I understand the reason. But I don't understand whether this > should be in the public API. This should not be needed for > compatibility reasons [0]. > Am I wrong? Any comment? > > [0] > http://www.mathworks.com/access/helpdesk/help/toolbox/control/ref/ltiisstable.html > Well, as long as an extension doesn't break compatibility with Matlab- specific code, I don't see a problem. FYI: I added a tolerance for margin (not ported yet) as well, which isn't available for Matlab, and I extended feedback to allow things like sys = feedback (sys) or sys = feedback (sys, "+") (Matlab requires feedback (sys, eye(size(sys))) and feedback (sys, eye(size (sys)), +1) for closing a loop). Both extensions don't prevent pure Matlab-code from running. IMHO such extensions are common practice in Octave development, e. g. the string delimiters "string" instead of 'string' to name a prominent one. > > [...] > >> BTW: You may encounter the expression digital = ! isct (sys) in my >> code. It means that static gains are treated as continuous systems. >> Note that it is not the same as digital = isdt (sys), where static >> gains would be treated as discrete systems. > > This case should be present in the test cases I added (see above). > > > > Cheers, > Luca Favatella Regards, Lukas ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Octave-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/octave-dev
