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Julien Martin | 1 Aug 2010 15:06
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Problem using solve...

Hello,

I am trying to solve the following equation using Maxima:

eq:(m_plus*(S/SS)^m_plus*(SS-E))/S=1

Using the following command:

solve([eq], [SS]);

I get a solution that itself contains SS!! i.e.

SS=(m_plus*E*(S/SS)^m_plus+S)/(m_plus*(S/SS)^m_plus)

What I am getting wrong?

Thanks in advance,

Julien.
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http://www.math.utexas.edu/mailman/listinfo/maxima
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Barton Willis | 1 Aug 2010 16:00
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Re: Problem using solve...

See the user documentation for solveexplicit. 

I suspect that your equation doesn't have a solution using 
functions that Maxima knows about. I think you'll need to 
use a numerical method, not an exact solution. 

--Barton

-----maxima-bounces <at> math.utexas.edu wrote: -----

>To: maxima <at> math.utexas.edu
>From: Julien Martin <balteo <at> gmail.com>
>Sent by: maxima-bounces <at> math.utexas.edu
>Date: 08/01/2010 08:06AM
>Subject: [Maxima] Problem using solve...
>
>Hello,I am trying to solve the following equation using Maxima:
>eq:(m_plus*(S/SS)^m_plus*(SS-E))/S=1
>Using the following command:
>solve([eq], [SS]);
>
>I get a solution that itself contains SS!! i.e.
>SS=(m_plus*E*(S/SS)^m_plus+S)/(m_plus*(S/SS)^m_plus)
>What I am getting wrong?
>
>Thanks in advance,
>Julien.
>_______________________________________________
>Maxima mailing list
>Maxima <at> math.utexas.edu
>http://www.math.utexas.edu/mailman/listinfo/maxima
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Robert Dodier | 1 Aug 2010 19:08
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Maxima CVS backups?

Hi,

I seem to recall that someone is making backups of
the Maxima CVS repo (not just the current state of
all the files). Is that right? If so, where are the backups
stored?

I don't feel any need to move the backups to an "official"
place (whatever that might be), I just am wondering for
future reference where we stand.

Thanks for any information.

best

Robert Dodier
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Raymond Toy | 1 Aug 2010 20:35
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Re: Maxima CVS backups?

 On 8/1/10 1:08 PM, Robert Dodier wrote:
> Hi,
>
> I seem to recall that someone is making backups of
> the Maxima CVS repo (not just the current state of
> all the files). Is that right? If so, where are the backups
> stored?
I've been making monthly backups on the 15th of each month of other
projects.  I can easily add maxima to my list.  The backups reside on a
harddrive at home.  I keep about 6 mo to 1 year of backups.

Once in a long while, I also save to them to DVDs.

Ray
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Stavros Macrakis | 1 Aug 2010 22:48
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Re: Problem using solve...

Equations like yours can't be solved using the usual algebraic, trigonometric, and exponential functions.  In cases like this, Maxima normally rewrites the equation into another (ideally, simpler) form, which you can then try solving numerically.  If you don't want Maxima to do that, set solveexplicit:true.


The solutions to equations like yours involve the Lambert W function, which Maxima currently does not use for solving equations, though it does support its numerical evaluation (function lambert_w).  You might want to check the Wikipedia article on the Lambert W.  You can probably transform your equation into one solvable using lambert_w (but I don't guarantee it!).

              -s

On Sun, Aug 1, 2010 at 09:06, Julien Martin <balteo <at> gmail.com> wrote:
Hello,
I am trying to solve the following equation using Maxima:

eq:(m_plus*(S/SS)^m_plus*(SS-E))/S=1

Using the following command:

solve([eq], [SS]);

I get a solution that itself contains SS!! i.e.

SS=(m_plus*E*(S/SS)^m_plus+S)/(m_plus*(S/SS)^m_plus)

What I am getting wrong?

Thanks in advance,

Julien.

_______________________________________________
Maxima mailing list
Maxima <at> math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima


_______________________________________________
Maxima mailing list
Maxima <at> math.utexas.edu
http://www.math.utexas.edu/mailman/listinfo/maxima
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Robert Dodier | 1 Aug 2010 23:39
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Maxima 5.22.0

Hi, I;ve tagged version-5_22_0 in CVS and built rpms
and tar.gz and upload them all to SF.
Should be available real soon now at:
http://sourceforge.net/projects/maxima/files/
(looks like the list hasn't been refreshed yet, I don't
know what the refresh schedule is)

If someone can build & upload a Windows installer that
would be great.

As ever please give the new version a try and if/when
there aren't too many complaints I'll make a general announcement.

best

Robert Dodier
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Barton Willis | 2 Aug 2010 00:01
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Re: Problem using solve...

-----maxima-bounces <at> math.utexas.edu wrote: -----

>The solutions to equations like yours involve the Lambert W function,
>which Maxima currently does not use for solving equations, though it does
>support its numerical evaluation (function lambert_w). 

The to_poly_solver makes some effort to solve equations using the Lambert W function.

 (%i4) load(to_poly_solver)$

 (%i14) %solve(x * exp(x)=y,x);
 (%o14) %union([x=lambert_w(y)])

 (%i15) %solve(x^2 * exp(x^2)=y,x);
 (%o15) %union([x=%e^(%i*%pi*%z101)*sqrt(lambert_w(y))])

 (%i16) %solve(exp(1/x)/x = y,x);
 (%o16) %union([x=%e^(-2*%i*%pi*%z107)/lambert_w(y)])

In general, Lambert solver is weak:

 (%i18) %solve(exp(1/x) = x*y,x);
 Unable to solve
 Unable to solve
 Unable to solve
 (%o18) %solve([%e^(1/x)=x*y],[x])

--Barton
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prabhu | 2 Aug 2010 00:49
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Connecting from Matlab to Maxima

Hi all,


I was trying to connect Maxima from Matlab and use its symbolic capabilities.
The reason why I want to use Maxima is that Matlab's Symbolic toolbox cannot be
compiled, but I may have to create an executable for my code (with the code
still being available for download). I referred through the threads with similar 
topic, but am unable to find the exact answer.

Can we connect Maxima from Matlab and compile the entire code ? Did 
anyone do this before ? If yes, how can I communicate from Maxima to Matlab?

Thank you very much
Prabhakar
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Richard Fateman | 2 Aug 2010 01:00
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Re: Connecting from Matlab to Maxima

prabhu wrote:
Hi all,

I was trying to connect Maxima from Matlab and use its symbolic capabilities.
The reason why I want to use Maxima is that Matlab's Symbolic toolbox cannot be
compiled,
Huh? the symbolic toolkit is a package that is already compiled.
but I may have to create an executable for my code (with the code
still being available for download).
Maxima does not generally create "executables" for download.
I referred through the threads with similar 
topic, but am unable to find the exact answer.
Your question does not seem to maek sense.


Can we connect Maxima from Matlab and compile the entire code ?
What code are you referring to?  Maxima itself is already compiled (Lisp).

Perhaps you are misusing at least some of the words:  compile, code, executable, download?

Did 
anyone do this before ? If yes, how can I communicate from Maxima to Matlab?
One way would be for Maxima to print out a ".m" file and matlab to read it in.


Thank you very much
Prabhakar
_______________________________________________ Maxima mailing list Maxima <at> math.utexas.edu http://www.math.utexas.edu/mailman/listinfo/maxima 

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Harald Geyer | 2 Aug 2010 02:43
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Re: Maxima CVS backups?

> Hi,
> 
> I seem to recall that someone is making backups of
> the Maxima CVS repo (not just the current state of
> all the files). Is that right? 

I'm doing backups via the documented rsync method every
now and then, but not regularly/automatically so this is
not really a reliable backup.

Recently I started considering to do backups via
git-cvsimport. That might be of some use by itself.

> If so, where are the backups stored?

On various servers I have access to.
Currently at University of Vienna (Austria) and
http://wiki.42.lefant.net (Germany)

Harald
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