Halfway symbolic halfway numeric evaluation on wxMAXIMA

Hello members:

I have just recently adapted MAXIMA in my teaching for science education
and physics majors in class - the symbolic math is key and the biggest
motivator for students to have computer aided solution (to augment the
previous class training on long hand calculus and ODE etc.).

It seemed that when I started using real values on the my sheet towards the
of end of my worksheet the earlier cells simply adapted and lost all my
symbols and computed numerically?  Is the effect of say having assigned a
value to a symbol say R:100, C:100e-6, L:35e-3 (from a problem in network
analysis) global?

Will it be possible that I can selectively just on the same worksheet
enable symbolic on this cell and  that or from here to there?

Thanks this is such a wonderful teaching tool for me.

Regards,
Berns B.
USC Dept. of Physics (Cebu,Philippines)


On Wed, Apr 17, 2013 at 7:25 AM, <maxima-request at math.utexas.edu> wrote:

> Send Maxima mailing list submissions to
>         maxima at math.utexas.edu
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         http://www.math.utexas.edu/mailman/listinfo/maxima
> or, via email, send a message with subject or body 'help' to
>         maxima-request at math.utexas.edu
>
> You can reach the person managing the list at
>         maxima-owner at math.utexas.edu
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Maxima digest..."
>
>
> Today's Topics:
>
>    1. Re: program works with maxima 5.29.1 but freezes  with    maxima
>       5.30.0 (Rupert Swarbrick)
>    2. Re: program works with maxima 5.29.1 but freezes  with    maxima
>       5.30.0 (Dmitry Shkirmanov)
>    3. Re: The wiki is back (Jaime Villate)
>    4. Re: DiracDelta (Richard Hennessy)
>    5. dependencies (Edwin Woollett)
>    6. Getting the coefficients of a polynomial (Stavros Macrakis)
>    7. Re: The wiki is back (Robert Dodier)
>    8. Re: Getting the coefficients of a polynomial (Richard Fateman)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 16 Apr 2013 18:34:18 +0100
> From: Rupert Swarbrick <rswarbrick at gmail.com>
> To: maxima at math.utexas.edu
> Subject: Re: [Maxima] program works with maxima 5.29.1 but freezes
>         with    maxima 5.30.0
> Message-ID: <qle04axqr7.ln2 at skate.rswarbrick>
> Content-Type: text/plain; charset="us-ascii"
>
> Dmitry Shkirmanov <piminusmeson at bk.ru> writes:
> > It seems that expand, not subst causes the problem. Does maxima show
> > you the expr1 in the end of the attached program? I cannot see it,
> > maxima consums all available memory and just hangs up.
>
> Well, I was running Maxima in a terminal / Emacs. I got a few pages of
> text before hitting Ctrl-C to interrupt the printing.
>
> The problem isn't expand though, I wouldn't think. It's almost certainly
> operating correctly. I expect that the problem is that what you are
> expanding is huge...
>
> Rupert
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: not available
> Type: application/pgp-signature
> Size: 315 bytes
> Desc: not available
> URL: <
> http://www.math.utexas.edu/pipermail/maxima/attachments/20130416/80905a51/attachment-0001.pgp
> >
>
> ------------------------------
>
> Message: 2
> Date: Tue, 16 Apr 2013 22:38:28 +0400
> From: Dmitry Shkirmanov <piminusmeson at bk.ru>
> To: maxima at math.utexas.edu
> Subject: Re: [Maxima] program works with maxima 5.29.1 but freezes
>         with    maxima 5.30.0
> Message-ID: <516D9AA4.80008 at bk.ru>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> >
> > The problem isn't expand though, I wouldn't think. It's almost certainly
> > operating correctly. I expect that the problem is that what you are
> > expanding is huge.
> >
> > My *guess* is that something simplified massively when you did the big
> > substitution on the previous version of Maxima
>
> It seems that you are right. "expand(factor(test2))"  returns good
> answer while  "expand(test2)"  consumes all available memory.  I just
> added the "factor" command manually. Now everything works as expected,
> so problem solved.
>
> Thank you very much for help.
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 16 Apr 2013 20:14:07 +0100
> From: Jaime Villate <villate at fe.up.pt>
> To: maxima at math.utexas.edu
> Subject: Re: [Maxima] The wiki is back
> Message-ID: <516DA2FF.8040600 at fe.up.pt>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> If you access https://sourceforge.net/p/maxima/admin/wiki/permissions
> you can control who can do several different actions in the wiki: admin,
> configure, create, delete, edit, etc.
> I added "Developer" to almost all actions.
> You will notice that there is a group called "General", which is what I
> was planning to use; I have granted
> permission to create new wiki pages or edit the existing ones to the
> group General, which is currently empty.
>
> I have checked in https://sourceforge.net/p/maxima/admin/groups/ that by
> having granted those permissions in the wiki the general permissions for
> that Group have not changed, so I think that the wiki permissions will
> not interfere with git and other sections.
>
> We could then add users in the General group through
> https://sourceforge.net/p/maxima/admin/groups/
> Do you agree with this? Do you see any potential problems?
>
> Regards,
> Jaime
>
> On 04/16/2013 05:32 PM, Robert Dodier wrote:
> > On 2013-04-16, Jaime Villate <villate at fe.up.pt> wrote:
> >
> >> the new wiki, using the new Sourceforge software, is now active. It can
> >> be accessed from the homepage. The FAQ is now back in the Wiki.
> >> All developers with git access should also be able to modify the wiki
> >> (please do). Other people who would like to help us with the wiki,
> >> should be registered in Sourceforge and can  then send me a message
> >> telling me the sourceforge username and what they would like to help
> with.
> > Terrific. What is the procedure for a project administrator to grant
> > write permission to a non-developer? Is there a way to get a list of all
> > users who have write permission?
> >
> > best
> >
> > Robert Dodier
> >
> > _______________________________________________
> > Maxima mailing list
> > Maxima at math.utexas.edu
> > http://www.math.utexas.edu/mailman/listinfo/maxima
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 16 Apr 2013 16:10:27 -0400
> From: "Richard Hennessy" <rich.hennessy at verizon.net>
> To: "Rupert Swarbrick" <rswarbrick at gmail.com>
> Cc: maxima at math.utexas.edu
> Subject: Re: [Maxima] DiracDelta
> Message-ID: <E48EDF6ADAFB40EC8B1149A86DE8E6FC at RichsLaptop>
> Content-Type: text/plain; charset="utf-8"
>
> On Apr 16, 2013 1:59 AM, "Richard Hennessy" <rich.hennessy at verizon.net>
> wrote:
> > Sorry if that confused anyone.  I am not just trying to solve
> integrate(pwdelta(x-a)*f(x),x) but also integrate(diff_pwdelta(i,x-a)
> *f(x),x).
>
> Ok but, to solve that, you can just use integration by parts, right? Since
> delta only picks up stuff at zero, you don't even have to worry about
> boundary values.
>
> Rupert
>
> Yes, integrate(du*v) = ?integrate(u*dv) because u*v = 0.
>
> Rich
>
> -------------- next part --------------
> URL: <
> http://www.math.utexas.edu/pipermail/maxima/attachments/20130416/74cb5f86/attachment-0001.html
> >
>
> ------------------------------
>
> Message: 5
> Date: Tue, 16 Apr 2013 13:48:49 -0700
> From: "Edwin Woollett" <woollett at charter.net>
> To: "maxima mailing list" <maxima at math.utexas.edu>
> Subject: dependencies
> Message-ID: <60851BD48471466EB3CBDC377D6F7865 at edwinc367e16bd>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>         reply-type=original
>
> The Maxima help manual states that
> dependencies is a list of atoms which have a
> functional dependence, assigned by depends or
> gradef.
>
> The help manual omits that dependencies is
> also a function:
>
> (%i1) dependencies;
> (%o1)                                 []
> (%i2) depends(u,t);
> (%o2)                               [u(t)]
> (%i3) dependencies;
> (%o3)                               [u(t)]
> (%i4) dependencies(a(t));
> (%o4)                               [a(t)]
> (%i5) dependencies;
> (%o5)                            [u(t), a(t)]
>
>
> Ted Woollett
>
>
>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 16 Apr 2013 17:40:26 -0400
> From: Stavros Macrakis <macrakis at alum.mit.edu>
> To: maxima mailing list <maxima at math.utexas.edu>
> Cc: ????? ??????? <akritas at uth.gr>
> Subject: Getting the coefficients of a polynomial
> Message-ID:
>         <
> CACLVabX-7bBGZVSTUwA59WqDQB9GqKXdddmtFPpQK3hyQr3imw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> How can I get the coefficients of a polynomial in x?
>
> Clearly I first put into into CRE form with main variable x:
>
>      poly: rat(input_poly,x)$
>
> Then what?  The internal form of the CRE lets you just "read off" the
> coefficients at this point, but I can't think of any Maxima function that
> lets you access that.
>
> I can loop like this:
>
>      coefs(p,v):=block([l:[]],while p # 0 do
> (l:cons(r:ratcoef(p,v,0),l),p:(p-r)/v),l)
>
> but that seems like an awful lot of work (*n* polynomial divisions).  It
> also isn't very efficient for sparse polynomials like x^20000.  You could
> do similar things with bothcoef or ratcoef, but again you end up building
> *n
> * intermediate polynomials as you remove terms.
>
> You might think you could use ratcoef for i:0..*n*, but how do you
> determine *n*?  hipow is inefficient in that it converts the expression
> into general representation first (!).
>
> Am I missing some obvious solution, or do we need to add rat_hipow and
> rat_coeffs or something?
>
>       rat_hipow(x^3+a*x+1,x) => 3
>       rat_coeffs(x^3+a*x+1,x) => [[3,1],[1,a],[0,1]]
>
> Edge cases to think about: CREs with negative powers, cf.
> ratcoef(1/x^3,x,-3) => 1, ratcoef(a/(b-x),x,-5) => -a*b^4, etc.
>
>            -s
> -------------- next part --------------
> URL: <
> http://www.math.utexas.edu/pipermail/maxima/attachments/20130416/4a181d49/attachment-0001.html
> >
>
> ------------------------------
>
> Message: 7
> Date: Tue, 16 Apr 2013 22:53:38 +0000 (UTC)
> From: Robert Dodier <robert.dodier at gmail.com>
> To: maxima at math.utexas.edu
> Subject: Re: [Maxima] The wiki is back
> Message-ID: <kkkkpi$bcs$1 at ger.gmane.org>
>
> On 2013-04-16, Jaime Villate <villate at fe.up.pt> wrote:
>
> > Do you agree with this? Do you see any potential problems?
>
> OK by me.
>
> best
>
> Robert Dodier
>
>
>
> ------------------------------
>
> Message: 8
> Date: Tue, 16 Apr 2013 16:25:00 -0700
> From: Richard Fateman <fateman at eecs.berkeley.edu>
> To: Stavros Macrakis <macrakis at alum.mit.edu>
> Cc: maxima mailing list <maxima at math.utexas.edu>, ????? ???????
>         <akritas at uth.gr>
> Subject: Re: [Maxima] Getting the coefficients of a polynomial
> Message-ID: <516DDDCC.5070909 at eecs.berkeley.edu>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> It seems to me that if you want to create an array of coefficients,
> there are a couple of things:
> sparse or dense?
>
> e.g.  is  5*x^4+1   supposed to be [5,0,0,0,1]   or [[5,4],[0,1]]?
>
>
> On 4/16/2013 2:40 PM, Stavros Macrakis wrote:
> > How can I get the coefficients of a polynomial in x?
> >
> > Clearly I first put into into CRE form with main variable x:
> >
> >      poly: rat(input_poly,x)$
> >
> > Then what?  The internal form of the CRE lets you just "read off" the
> > coefficients at this point, but I can't think of any Maxima function
> > that lets you access that.
> >
> > I can loop like this:
> >
> >      coefs(p,v):=block([l:[]],while p # 0 do
> > (l:cons(r:ratcoef(p,v,0),l),p:(p-r)/v),l)
>
> better would be somegthing like this  (no division, no re-ratting.)
>
>     coefs(p,v) := (p:rat(p,v), block([l:[]], while p#0 for i:hipow(p,v)
> step -1 thru 0 do(  l:cons(r:ratcoef(p,v,i), p:p-r*v^i))  , l));
>
> >
> > but that seems like an awful lot of work (/n/ polynomial divisions).
> >  It also isn't very efficient for sparse polynomials like x^20000.
> >  You could do similar things with bothcoef or ratcoef, but again you
> > end up building /n/ intermediate polynomials as you remove terms.
> >
> > You might think you could use ratcoef for i:0../n/, but how do you
> > determine /n/?  hipow is inefficient in that it converts the
> > expression into general representation first (!).
> >
> > Am I missing some obvious solution, or do we need to add rat_hipow and
> > rat_coeffs or something?
>
> rat_hipow(p,x):= ?cadadr(rat(p,x))
>
> >
> >       rat_hipow(x^3+a*x+1,x) => 3
> > rat_coeffs(x^3+a*x+1,x) => [[3,1],[1,a],[0,1]]
> >
> > Edge cases to think about: CREs with negative powers, cf.
> > ratcoef(1/x^3,x,-3) => 1, ratcoef(a/(b-x),x,-5) => -a*b^4, etc.
> >
> >            -s
> >
> >
> >
> > _______________________________________________
> > Maxima mailing list
> > Maxima at math.utexas.edu
> > http://www.math.utexas.edu/mailman/listinfo/maxima
>
> -------------- next part --------------
> URL: <
> http://www.math.utexas.edu/pipermail/maxima/attachments/20130416/0e74c18f/attachment.html
> >
>
> ------------------------------
>
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
> http://www.math.utexas.edu/mailman/listinfo/maxima
>
>
> End of Maxima Digest, Vol 81, Issue 28
> **************************************
>