Date sent: Wed, 22 Jun 2005 23:45:19 +0200 (CEST) From: "Richard B. Kreckel" <kreckel@ginac.de> To: GiNaC discussion list <ginac-list@ginac.de> Subject: Re: [GiNaC-list] ginsh as a subroutine? Send reply to: Richard.Kreckel@ginac.de, GiNaC discussion list <ginac-list@ginac.de> <mailto:ginac-list-request@ginac.de?subject=unsubscribe> <mailto:ginac-list-request@ginac.de?subject=subscribe>
On Wed, 22 Jun 2005, John Fletcher wrote:
I would like to be able to call a subroutine with a string e.g.
"x+y"
and receive back an ex object containing the expression and also a map mapping "x" and "y" strings to symbol objects.
Well, ex::construct_from_string_and_lst(const string&, const ex&) expects you to provide the list of symbols.
That one aborts if the symbol is not in the list. I would prefer one which adds the missing symbols, and think that is best done as a map as there are not duplicate symbols with the same name. For example, if I process x = 1; it will make a symbol "x" with a key of "x" and if I then process y = x + 2; with the same map it will add "y" in the same way. I can always extract the symbols and also the names and e.g. make a list.
The example program ginsh does this internally. I think it could be added within the class for ex objects. Has anyone done this?
That sounds like a promising project. If it could parse strings like "expand((x+y)^2)", then this would be eminently useful for creating a decent interface for TeXmacs. There are a number of alternatives how to interface TeXmacs, but I'm under the impression that the cleanest way is via a string parser right inside the library, as opposed to the one in ginsh or yet another one outside GiNaC proper.
Regards -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>
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I take it then that this hasn't been done. Thanks for the comments John -- Dr John P. Fletcher Tel: (44) 121 204 3389 (direct line) Chemical Engineering and Applied Chemistry (CEAC), School of Engineering and Applied Science (SEAS), Aston University, Aston Triangle, BIRMINGHAM B4 7ET U.K. CEAC Web site http://www.ceac.aston.ac.uk/ FAX: (44) 121 204 3679