[LUGSB] texmacs and maxima

Sat Aug 9 22:02:44 EDT 2003

> But first, I invite you to join the TeXmacs users mailing list. You can
> find subscription details on www.texmacs.org. You'll pick up lots of neat
> tricks and Scheme macros to make your TeXmacs experience much more
> pleasant.

I am already on too many lists :( But if I get into too much trouble, I will 
:)

> First, you need to have Octave and/or Maxima installed and in your
> PATH environment variable so that TeXmacs can find it.
>
> Then, you just launch TeXmacs.

I found the bug.. I do have octave and maxima installed.. but I installed them 
after I had started texmacs the first time. Looks like texmacs checks for 
those program only on first start. So i delete ~/.TeXmacs directory and 
restarted the program.. now it does find octave and maxima! 

> For generating mathematical plots or functions within TeXmacs documents,
> Octave is probably the better choice. I am the author/maintainer of the
> Octave <-> TeXmacs code though, so I'm biased :) But.. last time I
> checked, Maxima couldn't generate a plot into TeXmacs.
>
> OTOH, the Maxima glue is a bit more stable than that for Octave.

I am using maxima because I need to solve 2 equations. Can this be done in 
Octave? In any case, as it turns out, I am not able to solve the equations in 
maxima.. But Maple solves the successfully. These are the three equations:

A = d*exp(-a*r^2);      eqn1
B = diff(eqn1,r);          eqn2
C = diff(eqn2,r);

Now I want to solve the three to get values of d, a, and r. A, B, C are 
constants. Maxima gives this output:

(C9) solve([D1,D2,D3]);
(D9)                      [[r = %R1, a = %R2, d = 0]]

I will be really glad if someone can point what I am doing wrong. The maxima 
commands I give are:

(C1) d*exp(-a*r^2);
(C2) diff(D1,r);
(C3) diff(D2,r);

and then the solve command (C9) above.

Thanks a lot!
Sarang

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sarang Lakare
mailto:sarang at users#sourceforge.net
web:http://www.cs.sunysb.edu/~lsarang/linux
!!Join the fight for freedom - Go GNU/Linux!!
>From mgraffam at mathlab.sunysb.edu Sun Aug 10 09:55:37 2003
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Date: Sun, 10 Aug 2003 09:56:56 -0400 (EDT)
From: Michael Graffam <mgraffam at mathlab.sunysb.edu>
To: Linux Users Group at Stony Brook <lugsb at fsl.cs.sunysb.edu>
Subject: Re: [LUGSB] texmacs and maxima
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On Sat, 9 Aug 2003, Sarang Lakare wrote:

> I am using maxima because I need to solve 2 equations. Can this be done in
> Octave? In any case, as it turns out, I am not able to solve the equations in
> maxima.. But Maple solves the successfully. These are the three equations:

No, Octave doesn't perform symbolic computations (yet?). It is a numerical
environment, like MATLAB.

> (C9) solve([D1,D2,D3]);
> (D9)                      [[r = %R1, a = %R2, d = 0]]
>
> I will be really glad if someone can point what I am doing wrong. The maxima
> commands I give are:
>
> (C1) d*exp(-a*r^2);
> (C2) diff(D1,r);
> (C3) diff(D2,r);
>
> and then the solve command (C9) above.

Well, right off the top you'll notice that nowhere in your computations
do you equate your expressions to your constants A,B,C. This is why
you get the bogus answer.

Here is how I solved your problem with Maxima:

GCL (GNU Common Lisp)  Version(2.4.0) Thu Mar 28 08:08:45 EST 2002
Licensed under GNU Library General Public License
Contains Enhancements by W. Schelter
Maxima 5.6 Thu Mar 28 08:08:39 EST 2002 (with enhancements by W. Schelter).
Licensed under the GNU Public License (see file COPYING)
(C1) d*exp(-a*r^2);

                                           2
                                      - a r
(D1)                              d %E
(C2) diff(D1,r);

                                               2
                                          - a r
(D2)                          - 2 a d r %E
(C3) diff(D2,r);

                                       2                2
                         2    2   - a r            - a r
(D3)                  4 a  d r  %E       - 2 a d %E
(C4) solve([A=D1,B=D2,C=D3],[a,d,r]);

                                             2
                                            B
                                     - ------------
                          2                       2
                   A C - B             2 A C - 2 B         A B
(D4)       [[a = - --------, d = A %E              , r = --------]]
                        2                                       2
                     2 A                                 A C - B
(C5)

Hope that helps.