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Sent: Sunday, September 18, 2005 11:15 PM
Subject: Maxima digest, Vol 1 #964 - 14 msgs
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> Today's Topics:
>
> 1. Macsyma vs. Maxima, book (Fred J.)
> 2. Re: Re: [Maxima-bugs] [ maxima-Bugs-1281737 ]
> limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus) - wrong (Milan Lukic)
> 3. Re: Macsyma vs. Maxima, book (Milan Lukic)
> 4. user difined functions and the init file (Fred J.)
> 5. Ignore. Test (Raymond Toy)
> 6. string functions (Robert Dodier)
> 7. Re: Fwd: plot2d cannot create maxout.gnuplot (Robert Dodier)
> 8. maxima / macsyma's language (Richard Fateman)
> 9. Re: Re: Fwd: plot2d cannot create maxout.gnuplot (Mario)
> 10. Re: [Maxima-bugs] [ maxima-Bugs-1281737 ]
> limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus)
> - wrong (Raymond Toy)
> 11. Maxima Archives partial download (Fred J.)
> 12. Re: Maxima Archives partial download (Robert Dodier)
> 13. in search of a userdir, was: plot2d cannot create maxout.gnuplot
> (Robert Dodier)
>
> --__--__--
>
> Message: 1
> Date: Fri, 16 Sep 2005 14:37:05 -0700 (PDT)
> From: "Fred J." <phddas at yahoo.com>
> To: Maxima <maxima at math.utexas.edu>
> Subject: Macsyma vs. Maxima, book
>
> I am looking for a book on Calculus using Maxima. I
> came across this link
> http://www.math.utexas.edu/pipermail/maxima/2003/004000.html
> which is 2 years old. it was helpful in suggesting 2
> books;
>
> Computer-Supported Calculus
> by Robert P. Gilbert, Adi Ben-Israel
> ISBN: 32118-2924-5
>
> Macsyma Tutorial for Calculus, by Richard N. Fell,
> Jones and Bartlett Publishers, Sudbury, Massachusetts,
> 1998
>
> 2 years have passed and before going and buy them I
> wanted to drop a post asking for suggestions.
>
> thank you
>
> __________________________________________________
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>
> Message: 2
> Date: Fri, 16 Sep 2005 16:52:01 -0700
> From: Milan Lukic <milan at eskimo.com>
> To: Maxima List <maxima at math.utexas.edu>
> Subject: Re: [Maxima] Re: [Maxima-bugs] [ maxima-Bugs-1281737 ]
> limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus) - wrong
>
> * Raymond Toy <rtoy at earthlink.net> [2005-09-16 12:34:18 -0400]:
>
>>
>> >
>> > I am puzzled by the introduction of log(-1) in the result. The
>> > problem in the bug is lim(f/g) type problem, where both lim(f) and
>> > lim(g) are finite, lim(g) # 0. I am wondering if Maxima's limit
>> > algorithm does include treating that kind of basic case, and if so,
>> > does Maxima "know" that limit(atan(x),x,inf)=%pi/2, and that
>> > limit(exp(-t),t,inf)=0?
>>
>> I thought the same, but for some reason, maxima didn't try f/g. But
>> clearly maxima does know the limits for atan and exp.
>>
> How difficult would it be to modify the Limits package to make sure
> that Maxima looks for the "easiest" possibilities first, such as
> checking lim(f), lim(g) and if those exists, if lim(g)#0?
>
>> >
>> > Back to the bug: For problems like one in the bug, I would like to
>> > believe that Maxima ought to be able to handle those staying in the
>> > domain of real numbers, and do "simple" evaluation lim(f)/lim(g).
>> > Perhaps yours "add %log to one of the special cases in simplimit
>> > (clause 3)." is going to do exactly that. I apologize if I missed that
>>
>> Unfortunately, no, that doesn't do that. What it does is prevent maxima
>> from doing lim(f(x)) = f(lim x) for finite x. This is wrong of course
>> if f(x) has discontinuities for finite values. I also don't understand
>> why sin, cos, and others are listed here.
>>
> Thanks for the clarification.
>
>> There are probably other possible approaches for the issue in bug
>> 1281737. The fix I made is really meant for the log bug, which
>> concidentally fixes bug 1281737.
>>
> Nobody is going to complain for getting two birds by one stone :)
>
>> > However, if Maxima has to run into limit(log(w(z)),z,a) type of
>> > thing, the it seems that the lim(log) =log(lim) does not hold if the
>> > limit point happens to be in the negative real axis. Your approach to
>> > evaluate limits of both real and imaginary part seem to be a good way
>> > to go, with a proviso - the sign of the imaginary part should be kept
>> > constant to ensure approach to the limit point either through the
>> > second or the third quadrant.
>>
>> I believe it does preserve the sign.
>>
>
> Are you sure about this? It seems to me that if Maxima says that
> log(-1)=%i*%pi, and if it keeps the track of the sign of the imaginary
> part in log(1-%i*x), then it should not return log(-1) for the
> limit(log(-1-%i*x),x,0,plus).
>
> Milan
>
>
>
>> Ray
>>
>> _______________________________________________
>> Maxima mailing list
>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>
> --
>
>
> --__--__--
>
> Message: 3
> Date: Fri, 16 Sep 2005 17:04:17 -0700
> From: Milan Lukic <milan at eskimo.com>
> To: Maxima <maxima at math.utexas.edu>
> Subject: Re: [Maxima] Macsyma vs. Maxima, book
>
> I am not familiar with those books, but Google produced the following
> link http://www.math.utexas.edu/pipermail/maxima/2003/004000.html that
> might help you make your decision.
> BTW, "Milan" mentinoned in that web page is not me.
> Milan
>
> * Fred J. <phddas at yahoo.com> [2005-09-16 14:37:05 -0700]:
>
>> I am looking for a book on Calculus using Maxima. I
>> came across this link
>> http://www.math.utexas.edu/pipermail/maxima/2003/004000.html
>> which is 2 years old. it was helpful in suggesting 2
>> books;
>>
>> Computer-Supported Calculus
>> by Robert P. Gilbert, Adi Ben-Israel
>> ISBN: 32118-2924-5
>>
>> Macsyma Tutorial for Calculus, by Richard N. Fell,
>> Jones and Bartlett Publishers, Sudbury, Massachusetts,
>> 1998
>>
>> 2 years have passed and before going and buy them I
>> wanted to drop a post asking for suggestions.
>>
>> thank you
>>
>> __________________________________________________
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>> Tired of spam? Yahoo! Mail has the best spam protection around
>> http://mail.yahoo.com
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>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>
> --
>
>
> --__--__--
>
> Message: 4
> Date: Fri, 16 Sep 2005 17:31:42 -0700 (PDT)
> From: "Fred J." <phddas at yahoo.com>
> To: Maxima <maxima at math.utexas.edu>
> Subject: user difined functions and the init file
>
> Hello
>
> using Maxima 5.9.1-9 under Debian with the emacs
> maxima-mode
> I want to define some user functions and make them
> available to use
> at the Maxima command line under Linux, emacs
> Maxima-mode.
> after reading some paragraphs from the ref. manual and
> in the User
> Guide second edition userg.pdf by Macsyma Inc from
> this link
> http://www.cs.berkeley.edu/~fateman/macsyma/docs/
> I could use some correction for what I did;
>
> *create the maxima initialization file to auto load
> when maxima
> starts. please comment on the content of the next 2
> files as I am very
> new to maxima.
>
> ~/mac-init.mac
> ****************************************
> /*
> Maxima commands which you place in this file will be
> executed each
> time you execute the command INITIALZIE_MAXIMA();
> which happens
> automatically whenever you start maxima.
> to load this file any other time, issue this at the
> maxima command:
> load("mac-init.mac")$
> */
>
> file_search_usage:ture$
> file_search:cons("~/home/sam/maxima/",file_search)$
> showtime:true$
> load("~/maxima/myFun.mac")$
> ******************************************************
>
>
> *create the file with user defined functions
> ~/maxima_fun/myFun.mac
> ***********************************
> /*written by "Barton Willis" <willisb at unk.edu> on
> maxima mailing list*/
> distance(p1,p2) := block([listarith : true],
> if listp(p1) and listp(p2) and length(p1) =
> length(p2) then (
> p1 : map('cabs, p1-p2),
> sqrt(p1.p1))
> else error("The arguments to 'distance' must be
> equal length
> lists"))
> ******************************************************
>
>
> the following might help
> (%i20) describe(INITIALZIE_MAXIMA);
>
> (%o20) FALSE
> (%i21) discribe(FILE_SEARCH);
>
> (%o21) discribe(FILE_SEARCH)
> (%i22) discribe(FILE_SEARCH_USAGE);
>
> (%o22)
> discribe([/usr/share/maxima/5.9.1/share/##.{usg,texi},
> /usr/share/maxim#
>
> a/5.9.1/share/{affine,algebra,calculus,combinatorics,contrib,contrib/nset,cont#
>
> rib/pdiff,diffequations,graphics,integequations,integration,macro,matrix,misc,#
>
> numeric,physics,simplification,specfunctions,sym,tensor,trigonometry,utils,vec#
>
> tor}/##.{usg,texi},
> /usr/share/maxima/5.9.1/doc/##.{usg,texi}])
> (%i23)
>
>
>
> __________________________________
> Yahoo! Mail - PC Magazine Editors' Choice 2005
> http://mail.yahoo.com
>
>
> --__--__--
>
> Message: 5
> Date: Sat, 17 Sep 2005 12:54:57 -0400
> From: Raymond Toy <rtoy at earthlink.net>
> To: Maxima List <maxima at math.utexas.edu>
> Subject: Ignore. Test
>
> test to maxima at math.utexas.edu.
>
> Ray
>
>
> --__--__--
>
> Message: 6
> Date: Sat, 17 Sep 2005 13:28:17 -0600
> From: Robert Dodier <robert.dodier at gmail.com>
> Reply-To: robert.dodier at gmail.com
> To: "van.Nek at gmx.net" <van.Nek at gmx.net>
> Cc: maxima <maxima at math.utexas.edu>
> Subject: string functions
>
> hi volker, you wrote in part:
>
>> My plans for the next future are to write a complete I/O and string
>> processing for Maxima.
>
> i mentioned in my previous message about numericalio for file i/o.
> i forgot to ask, what are the string operations you want?
>
> lisp provides some string operations.
> i guess it would be straightforward to create a maxima function
> for each lisp string function like this:
>
> (defun $upcase (s) (l2m-string (string-upcase (m2l-string s))))
>
> it turns out maxima strings are lisp symbols (not lisp strings).
> so it seems necessary to convert back and forth.
>
> (maxima strings are symbols because maclisp, the dialect in
> which maxima was originally written, didn't have strings.
> by chance or design, this is a useful feature, and i'm not concerned
> at this time to argue for using lisp strings as maxima strings.)
>
> for what it's worth,
> robert dodier
>
>
> --__--__--
>
> Message: 7
> Date: Sat, 17 Sep 2005 13:46:24 -0600
> From: Robert Dodier <robert.dodier at gmail.com>
> Reply-To: robert.dodier at gmail.com
> To: "van.Nek at gmx.net" <van.Nek at gmx.net>
> Cc: maxima <maxima at math.utexas.edu>
> Subject: Re: Fwd: plot2d cannot create maxout.gnuplot
>
> hi volker,
>
> one more comment -- you wrote in part,
>
>> I discovered Maxima to be a wonderful way for teaching a first
>> programming language combined with a CAS. To me and my
>> students it is both easy and powerful.
>
> i find the maxima language to be rather pleasant for programming.
> it is simple (which puts limits on what one can do, but for beginners
> that is not a problem), and it inherits from lisp the "everything is an
> expression" point of view.
>
> while we're on the topic, some language features which seem worth
> considering are lexical scope, closures, and a package system.
>
> for what it's worth,
> robert dodier
>
>
> --__--__--
>
> Message: 8
> Date: Sat, 17 Sep 2005 13:57:30 -0700
> From: Richard Fateman <fateman at cs.berkeley.edu>
> Organization: University of California, Berkeley
> To: robert.dodier at gmail.com
> CC: "van.Nek at gmx.net" <van.Nek at gmx.net>, maxima <maxima at math.utexas.edu>
> Subject: maxima / macsyma's language
>
> What may be obvious to some people, but not all, is that Maxima's
> language is one choice point, and there is nothing to
> prevent someone from adding another front end language
> that could, for example, be lisp syntax or Matlab syntax
> or even Mathematica syntax.
>
>
> The commercial macsyma can load and execute Matlab.m files,
> as well as translate from matlab.m to macsyma functions.
>
> The current language was designed in about 1967, and
> was influenced by Algol 60 and Lisp. It is also extensible
> in some ways by adding new operators.
>
> RJF
>
>
>
>
> Robert Dodier wrote:
>
>> hi volker,
>>
>> one more comment -- you wrote in part,
>>
>>
>>>I discovered Maxima to be a wonderful way for teaching a first
>>>programming language combined with a CAS. To me and my
>>>students it is both easy and powerful.
>>
>>
>> i find the maxima language to be rather pleasant for programming.
>> it is simple (which puts limits on what one can do, but for beginners
>> that is not a problem), and it inherits from lisp the "everything is an
>> expression" point of view.
>>
>> while we're on the topic, some language features which seem worth
>> considering are lexical scope, closures, and a package system.
>>
>> for what it's worth,
>> robert dodier
>>
>> _______________________________________________
>> Maxima mailing list
>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>
>
> --__--__--
>
> Message: 9
> From: Mario <biomates at telefonica.net>
> To: maxima at math.utexas.edu, robert.dodier at gmail.com
> Subject: Re: [Maxima] Re: Fwd: plot2d cannot create maxout.gnuplot
> Date: Sun, 18 Sep 2005 00:06:23 +0200
> Cc: "van.Nek at gmx.net" <van.Nek at gmx.net>
>
> Greetings,
>
>> > I discovered Maxima to be a wonderful way for teaching a first
>> > programming language combined with a CAS. To me and my
>> > students it is both easy and powerful.
>>
>> i find the maxima language to be rather pleasant for programming.
>> it is simple (which puts limits on what one can do, but for beginners
>> that is not a problem), and it inherits from lisp the "everything is an
>> expression" point of view.
>>
>
> I recognize in these paragraphs my own experience with Maxima.
>
> I like to teach maths with the assistance of a computer, and I have been
> an
> intensive user of java applets and spreadsheets as pedagogical tools.
>
> When I discovered Maxima, about twelve months ago, I began to think about
> the
> advantages and possibilities of such a program. Besides maths, I also
> teach
> some basic computing, and when I had to choose the programming language,
> my
> vote was for Maxima: so, my (high school) students learned to use a CAS
> and
> to write simple functions (with for-loops, conditionals and all that) with
> Maxima.
>
> Now, during this new academic year, some of those students will attend my
> math
> class, and they are already familiar with Maxima and how to program
> functions!
>
> My project for this course is to use Maxima as a mathematical laboratory.
> I'm
> very excited waiting for the results of this experience.
>
> Mario
> --
> --------------------------
> Mario Rodriguez Riotorto
> www.biomates.net
>
>
> --__--__--
>
> Message: 10
> Date: Sat, 17 Sep 2005 22:34:11 -0400
> From: Raymond Toy <rtoy at earthlink.net>
> To: Milan Lukic <milan at eskimo.com>, Maxima List <maxima at math.utexas.edu>
> Subject: Re: [Maxima-bugs] [ maxima-Bugs-1281737 ]
> limit(atan(x)/(1/exp(1)-exp(-(1+x)^2)),x,inf,plus)
> - wrong
>
> Milan Lukic wrote:
>
>>* Raymond Toy; rtoy at earthlink.net> [2005-09-17 12:13:49 -0400]:
>>
>>
>>
>>>Milan Lukic wrote:
>>>
>>>
>>>>* Raymond Toy <rtoy at earthlink.net> [2005-09-16 12:34:18 -0400]:
>>>>
>>>>
>>>>
>>>I was mistaken. It does try this first. However, it calls factor on
>>>the expression first, which converts it to
>>>atan(x)*exp((1+x)^2)/(exp(x^2+2*x)-1).
>>>
>>>But this is of the form inf/inf. At this point, I'm confused on exactly
>>> it's trying to do. More study needed if we really want to figure this
>>> out.
>>>
>>>
>>>
>>I tried to see what happens if L'Hospital's rule is used on
>>atan(x)*exp((1+x)^2)/(exp(x^2+2*x)-1). After
>>diff(numerator,x)/diff(denom,x),ratsimp; it is clear to the human eye
>>that (replacing atan(x) by %pi/2) that the new problem is basically a
>>quotient of two cubic polynomials, yet Maxima insists on log(-1). It
>>
>>
> I'd have to study the code some more to figure out why it insist on
> doing this.
>
>>>Perhaps log(-1) is intended to mean there's some ambiguity in the
>>>result? With the patch, limit(log(-1-%i*x),x,0,plus) returns -%i*%pi/2,
>>>preserving the appropriate sign and giving the expected answer.
>>>
>>>
>>>
>>This interpretation makes sense, at least for people who already know
>>that Maxima's handling of branch cuts is not full proof, but I would
>>be happier then if it would return Log(-1), and let the user figure
>>out which one of the branches applies in the particular case. Ideally,
>>
>>
> I think letting the user decide what log(-1) is is worse than not
> returning an answer at all. Even if the user knows about branch cuts,
> he'll end up having to do the derivation itself to figure out what
> branch to use. And if you don't know what branch cuts are, you're
> likely to choose the wrong answer.
>
> We should fix the deficiencies in maxima's understanding of branch cuts.
>
> But I agree, maxima probably should not have converted atan to log for
> so quickly.
>
>>I would prefer that it would return a correct and fully reliable
>>result - or, since at this stage of development, we cannot completely
>>trust its handling of logs, print some kind of warning.
>>BTW, did you mean -%i*%pi/2 or -%i*%pi above? I think that the later
>>is correct.
>>
>>
> Yes, that's my mistake. -%i*%pi/2 is for a different problem.
>
> Ray
>
>
> --__--__--
>
> Message: 11
> Date: Sun, 18 Sep 2005 13:47:47 -0700 (PDT)
> From: "Fred J." <phddas at yahoo.com>
> To: Maxima <maxima at math.utexas.edu>
> Subject: Maxima Archives partial download
>
> Hello
>
> did any body tried to download the whole archive and
> had the problem that it only downloads 19.0MB and
> stops?
> url: http://www.math.utexas.edu/pipermail/maxima/
> link tage: download the full raw archive
> tabe url:
> http://www.math.utexas.edu/pipermail/maxima.mbox/maxima.mbox
>
> regards.
> Fred, J.
>
> __________________________________________________
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> Tired of spam? Yahoo! Mail has the best spam protection around
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> --__--__--
>
> Message: 12
> Date: Sun, 18 Sep 2005 19:37:49 -0600
> From: Robert Dodier <robert.dodier at gmail.com>
> Reply-To: robert.dodier at gmail.com
> To: "Fred J." <phddas at yahoo.com>
> Subject: Re: [Maxima] Maxima Archives partial download
> Cc: Maxima <maxima at math.utexas.edu>
>
> Hello Fred,
>
>> did any body tried to download the whole archive and
>> had the problem that it only downloads 19.0MB and
>> stops?
>
> You might have better luck by downloading the gzip-compressed
> year-by-year archives. Those are a lot smaller, about 1 Mb per year.
> I've downloaded the year-by-year archives without problems.
>
> hope this helps,
> Robert Dodier
>
>
> --__--__--
>
> Message: 13
> Date: Sun, 18 Sep 2005 22:07:08 -0600
> From: Robert Dodier <robert.dodier at gmail.com>
> Reply-To: robert.dodier at gmail.com
> To: "Vadim V. Zhytnikov" <vvzhy at mail.ru>
> Cc: van.Nek at gmx.net, Maxima <maxima at math.utexas.edu>
> Subject: in search of a userdir, was: plot2d cannot create
> maxout.gnuplot
>
> hello vadim, you wrote:
>
>> Some write permission problem was my primary suspect.
>> And as far as I understand this is the case. A bit
>> strange that the problem shoved up only after some
>> Windows patches but this doesn't matter.
>> The fact that Plot2/3d damps data files in some quite
>> random place is bad. And this is actually bad on both
>> Windows and UNIX. Especially on Windows since
>> maxout.gnuplot directory depends even on the xmaxima
>> shortcut location. If xmaxima is invoked from
>> menu - one place, the same shortcut copied on
>> user desktop - another. So writing maxout.*
>> files in some definite location in user's directory
>> is definitely right idea. But I'm only not so sure
>> that maxima-userdir
>>
>> $HOME/.maxima on UNIX
>> %USERPROFILE%\maxima on Windows
>>
>> is the proper place. As Valker mention this directory
>> may be not existent. What about user home directory?
>> Just $HOME or %USERPROFILE% respectively.
>
> $HOME or %USERPROFILE% is OK by me.
> so is /tmp or c:\temp; however that is problematic, as it is not
> guaranteed that c:\temp exists, so far as i know.
>
> can someone make a patch to (1) assign a userdir variable if one
> is not already assigned, and (2) modify plot2d/plot3d to write
> the output file to the user directory (whatever is decided upon) ?
>
> when this problem is resolved, i want to go ahead with the 5.9.2 release.
> conversely, if this problem is not resolved, i am inclined to go ahead
> anyway -- a lot of stuff has changed since 5.9.1 and the benefit of
> allowing users to access the new version outweighs the lack of a
> fix for this particular problem.
>
> all the best,
> robert dodier
>
>
>
> --__--__--
>
> _______________________________________________
> Maxima mailing list
> Maxima at math.utexas.edu
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>
>
> End of Maxima Digest
>