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- Newsgroups: sci.math.symbolic
- Path: sparky!uunet!utcsri!torn!watserv2.uwaterloo.ca!watdragon.uwaterloo.ca!watdragon!drclark
- From: drclark@daisy.uwaterloo.ca (David R. Clark)
- Subject: Re: dumb maple question -- differential equations
- In-Reply-To: bagchi@eecs.umich.edu's message of Wed, 16 Dec 1992 23:40:06 GMT
- Message-ID: <DRCLARK.92Dec17110649@daisy.uwaterloo.ca>
- Sender: news@watdragon.uwaterloo.ca (USENET News System)
- Organization: University of Waterloo, Waterloo, Ontario, Canada
- References: <BAGCHI.92Dec16184006@quip.eecs.umich.edu>
- Date: Thu, 17 Dec 1992 16:06:49 GMT
- Lines: 59
-
- In article <BAGCHI.92Dec16184006@quip.eecs.umich.edu> bagchi@eecs.umich.edu (Ranjan Drzzzzt! Bagchi) writes:
-
- From: bagchi@eecs.umich.edu (Ranjan Drzzzzt! Bagchi)
- Subject: dumb maple question -- differential equations
-
- ... (header and sample session deleted)
-
- There are several things I'd like to do with this data which
- I haven't had much luck with:
-
- 1) I'd like to break v1(t), v2(t), pr(t) into separate functions. While
- this sounds trivial, the only way I've been able to do it is with
-
- V1 proc(t) op(2,op(2,pv(t))) end;
-
- which looks fairly inelegant.
-
- Unfortunately, because Maple's sets are unordered, the hardcoded "2" in
- the first op call above will cause problems. A more robust, but uglier,
- version is:
- V1 := proc(p)
- local i,v;
- v := pv(p);
- for i in v do
- if op(1,i) = 'v1(t)' then RETURN(op(2,i)) fi
- od;
- ERROR(`Could not find v1`);
- end;
-
- 2) I'd like to collect a large (say 10000 point) array of data from each
- of the functions. Any attempt at this has taken what seems to be
- an unbearably long time. I've been using a do loop and putting data
- in each array bucket.
-
- Generating 10000 points from dsolve will take a long time. We are working
- on speeding this up. The only suggestion I can make is to generate the
- points in order so that no unnecessarily large changes occur in the parameter
- value.
-
- 3) I'd like to plot these derived function. In the V1 I defined above,
- I get the following errors:
-
- > plot(V1,0..10);
- Error, (in f) wrong number (or type) of parameters in function type;
-
- I could not actually duplicate this error, but because of the set ordering
- problem I mention above the resulting plot was not useful. There is a
- command odeplot in the plots package for plotting the output of dsolve.
-
- help??
-
- -rj
- --
- Ranjan Bagchi Ranjan.Bagchi@umich.edu
- oo oooo o oo ooo oo oo oo o o oooo ooo o o oooooooo
-
- We, the SCG group at UW, are working on the dsolve package.
-
- David Clark
-