Re: control pkg

[Carnë Draug]

On 13 February 2012 14:52, Doug Stewart <address@hidden> wrote:
> 2012/2/13 Carnë Draug <address@hidden>
>> On 13 February 2012 14:38, Doug Stewart <address@hidden> wrote:
>> > 2012/2/13 Carnë Draug <address@hidden>
>> >> On 13 February 2012 14:07, Doug Stewart <address@hidden> wrote:
>> >> > I have
>> >> >
>> >> > octave:1> ver
>> >> >
>> >> > ----------------------------------------------------------------------
>> >> > GNU Octave Version 3.6.1-rc0
>> >> > GNU Octave License: GNU General Public License
>> >> > Operating System: Linux 2.6.32-38-generic #83-Ubuntu SMP Wed Jan 4
>> >> > 11:13:04
>> >> > UTC 2012 i686
>> >> >
>> >> > ----------------------------------------------------------------------
>> >> > Package Name   | Version | Installation directory
>> >> > ---------------+---------+-----------------------
>> >> >       control *|   2.2.4 | /home/doug/octave/control-2.2.4
>> >> > miscellaneous *|  1.0.11 | /home/doug/octave/miscellaneous-1.0.11
>> >> >         optim *|  1.0.17 | /home/doug/octave/optim-1.0.17
>> >> >        signal *|   1.1.2 | /home/doug/octave/signal-1.1.2
>> >> >       specfun *|   1.1.0 | /home/doug/octave/specfun-1.1.0
>> >> >        struct *|   1.0.9 | /home/doug/octave/struct-1.0.9
>> >> >
>> >> >
>> >> > i do:
>> >> >
>> >> > octave:2> help c2d
>> >> > error: help: `c2d' not found
>> >> >
>> >> > but
>> >> > octave:2> help tf
>> >> > `tf' is a function from the file
>> >> > /home/doug/octave/control-2.2.4/@tf/tf.m
>> >> >
>> >> >  -- Function File: S = tf ("S")
>> >> >  -- Function File: Z = tf ("Z", TSAM)
>> >> >  -- Function File: SYS = tf (SYS)
>> >> >  -- Function File: SYS = tf (N
>> >> >
>> >> >
>> >> > Why are some of the things in control pkg available and others are
>> >> > not?????
>> >> >
>> >> > Doug
>> >>
>> >>
>> >> This is explained in the manual here
>> >>
>> >>
>> >> http://www.gnu.org/software/octave/doc/interpreter/Creating-a-Class.html#Creating-a-Class
>> >>
>> >> Note that methods of a class can be documented. The help for the
>> >> constructor itself can be obtained with the constructor name, that is
>> >> for the polynomial constructor help polynomial will return the help
>> >> string. Also the help can be obtained by restricting the search for
>> >> the help to a particular class, for example help
>> >> @polynomial/polynomial. This second method is the only means of
>> >> getting help for the overloaded methods and functions of the class.
>> >>
>> >> The help text you are trying to access, is a function of the class so
>> >> you need to specify the class as in "help @lti/c2d".
>> >>
>> >> Carnë
>> >
>> >
>> > So the help is:
>> >> help @lti/c2d
>> > address@hidden/c2d' is a function from the file
>> > /home/doug/octave/control-2.2.4/@lti/c2d.m
>> >
>> >  -- Function File: SYS = c2d (SYS, TSAM)
>> >  -- Function File: SYS = c2d (SYS, TSAM, METHOD)
>> >  -- Function File: SYS = c2d (SYS, TSAM, "PREWARP", W0)
>> >      Convert the continuous lti model into its discrete-time equivalent.
>> > is this wrong?
>> > Doug
>>
>> No. This is correct. You call the function normally. But since the
>> first argument will be an object of the lti class, octave knows where
>> to look for the function/method. But when trying to access the help
>> text, octave does not know which c2d you're talking about so you must
>> specify the class. This allows for different classes to have methods
>> with the same name.
>>
>> Carnë
>
>
> How hard would it be to fix help so that it would work normaly for these
> functions?

Fix? I don't think there's anything to fix.

Imagine the situation where 2 classes have the same method. Which one
would help show? Such situation is not uncommon at all, specially with
display methods and overloading arithmetic operations. Just see on the
linear-algebra package the methods for the blksparse and kronprod
classes.

http://octave.sourceforge.net/linear-algebra/overview.html

Carnë