HDTenEightyP/NetNews huggingface dataset:
From: gerber@sirius.astro.uiuc.edu (Richard A. Gerber)
Subject: Maple can diff(expr), but not int(diff(exp))?
Organization: University of Illinois at Urbana
Date: Mon, 13 Apr 1992 15:56:41 GMT

I can get Maple to differentiate a simple expression, but then I can't
seem to get an answer if I ask it to calculate the indefinite integral
of that expression. Here's the problem:
------------------------------------------------------------------------------
> diff(BesselJ(1,x),x);
                                          BesselJ(1, x)
                          BesselJ(0, x) - -------------
                                                x

--------------------------------------------------------------------------------
> int(",x);
                        /
                       |                  BesselJ(1, x)
                       |  BesselJ(0, x) - ------------- dx
                       |                        x
                      /
------------------------------------------------------------------------------

Am I missing something, or is Maple V just not capable of this? Is it a 
problem with Bessel functions?

I discovered this after I tried to get Maple V to evaluate:

int(BesselJ(1,x)*exp(-x),x=0..infinity);

Maple could not find an answer for this even though it has a simple
analytic solution. The solution is in even very limited integral tables.

Regards,

 
--
-------------------------------------------------------------
Richard Gerber
Grad Student Physics
gerber@rigel.astro.uiuc.edu
University of Illinois @ Urbana-Champaign
-------------------------------------------------------------
From: jem@squid.ucsb.edu (Jennifer E. Magness)
Newsgroups: sci.math.symbolic
Subject: more imaginary numbers
Date: 17 Apr 92 16:28:35 GMT
Distribution: na
Organization: University of California, Santa Barbara
Originator: jem@squid


Thanks to all that replied to my first query - however, the
problem does not seem to be solved.  Here is a chunk of the 
original:

     >What I Want:                         What I Get Now:

     >(set type of variable somehow)                                 
     >In:=                                 In:=
     >Im[x + I y]                          Im[x + I y]

     >Out:=                                Out:=
     >y                                    Im[x + I y]

     >I need to use complicated functions for x and y, or
     >else doing the computations by hand would be no
     >problem.

OK, so I followed a few different folks' advice and
did this:

In:=
    x /: Re[x] = x;
    x /: Im[x] = 0;
    y /: Re[y] = y;
    y /: Im[y] = 0;
    z = x + I y;
    Re[z]
    Im[z]
Out:=
    Re[x + I y]
    Im[x + I y]

So what's the deal here?  Am I missing something?
The actual problem that I would eventually like to 
solve via Mma (which I have already done by hand) is:

f = (((w l I + r)/(w t I))/(w l I + r + 1/(w t I))) + 1/(w m I)
Im[f]

in order to find the imaginary part of this equation, which 
will allow me to solve for the resonance frequency of the
circuit for which I wrote the equation.  (where w is the 
frequency, l is the inductance, r is the resistance, t is the 
capacitance in parallel with the series LR, and m is the 
capacitance in series with the other circuit chunk).  It was
suggested to me to use Mma for this problem as a check, and
now it's almost more trouble than it's worth to finish this
problem!  Although I have had success with other problems
on Mma... 

BTW, I have tried ComplexExpand in various places and the output 
contains a lot of Abs's and I's, which is not what I need.  I 
assume that f above can be written as a sum of two numbers, 
ie A + Bi, however complicated A and B may be.

Please address replies to: jem%squid@hub.ucsb.edu

thanks, jennifer
dept of chemical and nuclear engineering
univ. of ca, santa barbara
From: jem@squid.ucsb.edu (Jennifer E. Magness)
Newsgroups: sci.math.symbolic
Subject: imaginary number
Date: 16 Apr 92 00:00:22 GMT
Article-I.D.: ucsbcsl.4198
Distribution: na
Organization: University of California, Santa Barbara
Originator: jem@squid

Imagine that I want to take the imaginary part of a number:

In:=
Im[4 + 0 I]

Out:=
0

----or------

In:=
Im[4]

Out:=
0

-------------
no big deal, right?

So, how do I tell Mma 2.0 that the variables x and y
in the following are real, so that if I ask for the 
imaginary part of z, I get y?  (without explicitly
setting a value to y)

What I Want:                         What I Get Now:

(set type of variable somehow)                                 
In:=                                 In:=
Im[x + I y]                          Im[x + I y]

Out:=                                Out:=
y                                    Im[x + I y]

I need to use complicated functions for x and y, or
else doing the computations by hand would be no
problem.

Please address replies to: jem%squid@hub.ucsb.edu

thanks, jennifer
dept of chemical and nuclear engineering
univ. of ca, santa barbara
Newsgroups: sci.math.symbolic
From: sharaf@cmb00.larc.nasa.gov (Hazem Sharaf El-Din)
Subject: Macsyma books, user guides, reference manuals
Originator: sharaf@cmb00.larc.nasa.gov
Organization: NASA Langley Research Center  Hampton VA  23665
Date: Thu, 9 Apr 1992 20:23:11 GMT

Hi,

I am trying to find good documentation for Macsyma. I have been
using it for sometime without and manuals except the online command 
description.

Thanks.

Hazem
From: d3a132@roark.oname (Carl P Baker)
Newsgroups: sci.math.symbolic
Subject: Re: Variable  ReadList input. How to ?
Date: 15 Apr 92 01:00:05 GMT
Article-I.D.: oracle.1992Apr15.010005.5096
Reply-To: d3a132@roark.oname
Organization: Sun Microsystems


In article 68470@yuma.acns.colostate.edu, flatau@lamar.ColoState.EDU (Piotr Flatau) writes:
>
>..
>I have a list of numbers somewhat like that
>
>3 1 2 3
>3 67 45 23
>3 1 8 9
>4 2 3 4 9
>
>where the firstnumber indicates how many numbers will follow.
>How do I  code
>
>ReadList["myfile", {Number, Number .....}]
>such that it sometimes reads-in 3 numbers and sometimes 
>4 (these which follow the first one). The problem originates
>when describing polyhedra as a linked list of vertices and faces.
>
>Peter

Here's an ugly hack to do this:

p=ReadList["myfile", Number] 
For[i=1, NumberQ[p[[1]]], i=i+1, a[i]=Take[p, p[[1]]]; p=Drop[p, p[[1]]+1]] 
b=Table[a[j], {j, 1, i}]

b will be the table you want.  Of course you end up with ugly variables (p, i and a)
left behind unless you implement this in a function.  Someone better at functional
programming than me can certainly write this better I think?

Carl
cp_baker@pnl.gov
From: engelsma@golden.cps.msu.edu (Engelsma Jonathan)
Newsgroups: sci.math.symbolic
Subject: Mathematica/Simultaneous Equations
Date: 8 Apr 92 16:05:37 GMT
Organization: Dept. of Computer Science, Michigan State University

I have a question regarding Mathematica.    I have a set of simultaneous
equations which includes both differential and algebraic equations.
Here is a simple example: (using Mathematica syntax)

       y'[t] == 2y[t]-z[t]
       z[t]  == t 100y[t]

I would like to solve for z[t] and y[t] with a command like:

	DSolve[{y'[t] == 2 y[t] - z[t], z[t] == 100 t y[t]}, 
		{y[t],z[t]},t]

However, Mathematica does not seem to handle it.  It is
the time-varying coefficient in the second equation which
seems to cause the problem.  The set of equations:

       y'[t] == 2y[t]-z[t]
       z[t]  == 100y[t]

can be solved with DSolve without any problem. The only way
I could find to solve the first set of equations was to first 
apply the transformation:

	 de1 = y'[t] == 2y[t]-z[t] /. {z[t]->t 100y[t]}

and then use:

	ysol = Part[ DSolve[{de1},y[t],t], 1]

to find y[t], and use:

	zsol = {z[t] -> 100 t y[t] /. ysol}

to find the solution for z[t].  

For this trivial example of course, there is no problem.  However,
I have a program which is generating very large sets of such 
simultaneous equations, and it would be not be acceptable to
use a method as illustrated above.   What I would like to do
is to simply present Mathematica a list of equations and
variables such as: 

eqset = {c1a[t] == 2t,
	c2b'[t] == 1/3 (c2a[t] - c2b[t]),
        c2b[0]  == 0,
	c3c[t]  == c3a[t] - c3b[t],
        c4b'[t] == c4a[t],
	c4b[0]  == 0,
        c1a[t]  == c2a[t],
        c2b[t]  == c3a[t],
	c3b[t]  == c4b[t],
        c3c[t]  == c4a[t]}

vars = {c1a[t],c2a[t],c2b[t],c3a[t],c3b[t],c3c[t],c4a[t],c4b[t]}

and have Mathematica do all the work in a single function invocation, 
such as:

	MagicallySolveThisMess[eqset,vars,t]

and, receive back a list of solutions for the various vars as a function
of t.  The question is how do I define MagicallySolveThisMess[]?  Is
there a predefined function that already does this?   Why doesn't
DSolve handle it?  Can anybody point me in the right direction?

Thanks!

-------------------------------------------------------------------------
Jonathan R. Engelsma                            Michigan State University
                                                     Department of
E-mail:   engelsma@cps.msu.edu                     Computer Science
	  uunet!frith!engelsma	
	  uunet!frith!jresys!engelsma (home)	
-------------------------------------------------------------------------
From: phr@soda.berkeley.edu (Paul H. Rubin)
Newsgroups: sci.math.symbolic
Subject: MMA for Windows---should I spring for the upgrade?
Date: 13 Apr 92 14:49:08 GMT
Article-I.D.: soda.PHR.92Apr13094908
Organization: CSUA/UCB
NNTP-Posting-Host: soda.berkeley.edu

I have MSDOS Mathematica 2.0 (text-only interface) and I hear the
Notebook interface is quite an improvement for interactive use.
However, I've seen reports that early releases of MMA/Windows were buggy.
Does anyone know if there have been more recent releases that are fixed?
If not, does the improved interface outweigh the bugs anyway?
Thanks.  (I'll summarize e-mail responses if I get any).
--Paul
Newsgroups: sci.math.symbolic
From: SOWELL@Zeus.unomaha.edu (Glenn Sowell)
Subject: MathCAD question
Organization: University of Nebraska at Omaha
Date: Tue, 14 Apr 1992 17:19:12 GMT
X-News-Reader: VMS NEWS 1.11

I am not sure that this is the correct forum for a MathCAD question (is 
there a better one?) but here goes:

  We want to put MathCAD for the Macintosh on a fileserver running Appleshare.
(Yes we have a license to do so.) The problem is that only one user can 
access the program at a time. We have tried some of the usual tricks but 
nothing seems to work. And the company is not very forthcoming with help!

  Does anyone out there have experience with MathCAD on a network?

Thanks for the help.
Glenn Sowell
Dept. of Physics
University of Nebraska at Omaha
sowell@zeus.unomaha.edu

Newsgroups: sci.math.symbolic
From: coker@dirac.physics.sunsyb.edu (David Coker)
Subject: Re: Science Article About Symbol Manipulation
Organization: Institute for Theoretical Physics, SUNY at Stony Brook
Date: Fri, 17 Apr 1992 02:57:20 GMT
Keywords: Symbol Manipulation

In article <qb1jmq+@lynx.unm.edu> stanly@crunch..unm.edu (Stanly Steinberg) writes:
>
>The 3 April 1992 Science magazine has a section called
>"Computers in Science" which has a section called
>"Bringing the Computer Revolution Down to a Personal Level"
>which begins with a section called 
>"Software for solving equations" that is about symbol manipulation.
>Mathematica is emphasized, but most systems are mentioned.
>I am not impressed by the accuracy of the article!
>--
>Professor Stanly Steinberg, Department of Mathematics and Statistics
>University of New Mexico, Albuquerque, NM 87131-1141, 505-277-5323
>stanly@math.unm.edu    stanly@unmb.bitnet
>FAX 505-277-5505 (or at Ecodynamics 505-843-9641)


Just a note to point out that I agree with the above. However, some
-- 
David A. Coker
______________________________________________________________
coker@max.physics.sunysb.edu
From: suthan@cs.hw.ac.uk (Manickam Umasuthan)
Newsgroups: sci.math.symbolic
Subject: Mma
Date: 10 Apr 92 14:37:01 GMT
Organization: Dept of Computer Science, Heriot-Watt University, Scotland

I shall be thankful if someone kindly let me know the ftp sites for
Mathematica packages. I am looking for a package in differential
geometry.
THANKS
-- 
-------
M.Umasuthan, 
Dept. of Comp. Sci.,Heriot-Watt University,
Edinburgh, EH1 2HJ  U.K. :: EMAIL:  suthan@uk.ac.hw.cs
From: watson@clark.edu (Dennis Watson)
Newsgroups: sci.math.symbolic
Subject: Re: Maple V Release 2
Date: 8 Apr 92 17:28:11 GMT
Article-I.D.: clark.1992Apr8.172811.3919
Organization: Clark College, Vancouver, Wa.  USA

I recently purchased the student edition of Maple V.  It comes with a "by
example" manual called "Maple V Flight Manual."  What I need is access
to the Maple Reference Manuals! And the modules that are not in the
student edition.  I am going to adopt it for use by my Calculus, etc.,
students but would like to be able to answer the questions the Flight
Manual doesn't answer.  Any help would be appreciated, esp. some place
to ftp the missing modules, etc.!
Thanx
Dennis Watson
watson@clark.edu
From: NCKUT057@twnmoe10.edu.tw
Newsgroups: sci.math.symbolic
Subject: How to get MathTensor?
Date: 11 Apr 92 07:14:52 GMT
Organization: Ministry of Education, Computer Center NETNEWS system V2.3

Dear sir,

   I want a Mathematica package: MathTensor, or any related packages

about general relativity. How could I get it? Please reply here or send

an E-mail to NCKUT057@TWNMOE10.EDU.TW . Thank you very much.

                                                            G.J.Cheng
From: stromme@math.utah.edu (Stein Stromme)
Newsgroups: sci.math.symbolic
Subject: Re: Macaulay
Date: 10 Apr 92 18:38:37 GMT
Article-I.D.: jeeves.STROMME.92Apr10113837
Organization: Department of Mathematics, University of Utah

In article <1992Apr10.040748.16845@timessqr.gc.cuny.edu> las@cunyvms1.gc.cuny.edu writes:

   I'm interested in getting information about a software capable
   of doing algebraic geometry over finite fields. I believe the
   name is Macaulay. I have also heard that this is a public doamin
   software. Thanks in advance.

Macaulay, by Dave Bayer and Michael Stillman. 
Available by anonymous ftp from zariski.harvard.edu.
Newsgroups: sci.math.symbolic
From: cabruen@athena.mit.edu (Charles Alan Bruen)
Subject: Help with Mathematica FrameLabel Command
Organization: Massachusetts Institute of Technology
Distribution: usa
Date: Tue, 14 Apr 1992 02:07:55 GMT

Hello:

I am trying to put labels on a 2D Mathematica using the label command.
Label1 which is the x-axis comes out find, but the y-axis prints the
characters going up like this.
	G
	N
	I
	R
	T
	S
Does anybody know how I can rotate the characters counter-clockwise 90 degrees.
The command I am giving looks like this

Plot[ Sin[x], {x,0,Pi},
	Frame->True,
	FrameLabel->{"X-axis", "Y-axis"}]

Thanks alot for the help.


Charles Bruen
cabruen@athena.mit.edu
Newsgroups: sci.math.symbolic
From: las@cunyvms1.gc.cuny.edu
Subject: Macaulay
Reply-To: las@cunyvms1.gc.cuny.edu
Organization: Computer Center, CUNY Graduate School, New York NY 10036
Date: Fri, 10 Apr 1992 04:07:48 GMT

I'm interested in getting information about a software capable
of doing algebraic geometry over finite fields. I believe the
name is Macaulay. I have also heard that this is a public doamin
software. Thanks in advance.
Newsgroups: sci.math.symbolic
Subject: Re: Dynamic programming packages?
From: hal@umich.edu (Hal Varian)
Date: Tue, 7 Apr 1992 01:59:57 GMT
Reply-To: hal@umich.edu (Hal Varian)
Organization: University of Arizona UNIX Users Group
Keywords: dynamic programming, Mathematica

In article <1992Apr6.112738.3217@bronze.ucs.indiana.edu>  
vbush@copper.ucs.indiana.edu (Victoria Bush) writes:
> I have had a barrage of requests for programs which will do dynamic 
> programming (usually time variant). Most of the people would be interested 
> in packages for Maple or Mathematica, but I would also like to include 
> any and all programs which will handle this... 

Here's a function definition that calculates the symbolic value function for a  
5-period intertemporal consumption-investment model with log utility.  What's  
remarkable is how simple this is in Mma since it handles the details of the  
recursion for you.

VV[w_,t_]:= VV[w,t] =
 Module[{c},
 Log[c] + alpha*VV[(w-c)*R,t+1]/.Solve[D[Log[c] 
        + alpha*VV[(w-c)*R,t+1],c]==0,c][[1]]]
VV[w_,5] := Log[w]

I'm editing a book called "Economic and Financial Modeling Using Mathematica".   
We should have a number of dynamic programming examples in the book.  Will  
probably be out late next Fall.
--
Hal Varian              hal@alfred.tucson.az.us
Department of Economics [On leave from U Michigan
University of Arizona   until April 29, 1992]
Tucson, AZ 85721        voice: 602-577-3578
Newsgroups: sci.math.symbolic
From: fletcher@socrates.umd.edu (Charles Fletcher)
Subject: MathLink (Update and semi-apology)
Keywords: MathLink
Organization: University of Maryland University College
Date: Fri, 10 Apr 1992 15:04:54 GMT

Well in the last couple of days I have come across a couple of things
that make me believe MathLink almost works (I still stand by my original
accessment and wouldn't bet the farm on it, but the simple examples
can be made to work.) These two things are:

1) Chuck Fleming posted a simple MathLink example (in connection with
ObjC on the NeXT) which works. Looking at his code I noticed some things
which were missing from mine.

2) I got to look at the most recent MathLink docs (although they are 
still stamped Preliminary. You should look for the WRI Tech Report on
MathLink with the Blue and White cover. This is probably free for the asking.)

Here is the key (to me at least):

   while (MLNextPacket(mylink) != RETURNPKT) MLNewPacket(mylink);

If you don't have this in your examples, you don't have the latest stuff.

I have now gotten the two simple examples in the docs and one of my own
working. Maybe there is hope.

Charlie




-- 
*********************************************************************
*	NeXTMail to:		*	...to confer, converse, and *
*	charlie@technosci.com	*	otherwise hobnob with my    *
*				*	fellow wizards.		    *
Newsgroups: sci.math.symbolic
From: haase@neuro.uchicago.edu (Mark Haase)
Subject: Waves and Diffusion
Summary: Interested in PDE packages available for Mathematica
Keywords: Mathematica, PDE, Parabolic PDE, Hyperbolic PDE
Organization: Dept. of Mathematics, U. of Chicago
Date: Wed, 8 Apr 1992 00:24:49 GMT

Dear Mathematica Users:

Are there any Mathematica routines available that will solve hyperbolic
or parabolic PDEs (eg., wave and heat equations)?  I plan to run a 
computer lab for a PDE class and would be very interested in any packages
that are available.  We plan to use Mathematica on the NeXT platform.
I have already consulted the books of "Mathematica by Example,"
"Programming in Mathematica," and Wolfram's "Mathematica."  
Thank you for your time.

Chris Haase
Dept. of Mathematics
University of Chicago


Newsgroups: sci.math.symbolic
From: fletcher@socrates.umd.edu (Charles Fletcher)
Subject: Re: Mathematica Does Some Incredibly Stupid Things!
Organization: University of Maryland University College
Date: Fri, 10 Apr 1992 14:48:24 GMT

In article <1992Apr9.233709.4306@EE.Stanford.EDU> siegman@EE.Stanford.EDU (Anthony E. Siegman) writes:
>Try
>
>   g1 = Plot[f[x], {x,0,1}, Frame->True]
>   Show[g1, FrameLabel->{,,"My Plot",}]
>
>You'll get "My Plot" on the top as desired; "Null" (which you didn't
>ask for) on the bottom; and
>
>     l               l
>     l               l
>     u               u
>     N               N          
>

	I got Null rotated 90 degrees--what version are you using?


>that's right, not even "Null" but "lluN", up both the right and left
>sides.  And as an added fillip the letters aren't centered as in the
>screen display here, but visibly left-justified, which makes things
>look even weirder.
>
>OK, I'll go back and and do it all over with
>
>    FrameLabel->{," "," ","My Plot", " "}.
		  ^
	Delete this comma.

Charlie


-- 
*********************************************************************
*	NeXTMail to:		*	...to confer, converse, and *
*	charlie@technosci.com	*	otherwise hobnob with my    *
*				*	fellow wizards.		    *
Newsgroups: sci.math.symbolic
From: sibley@math.psu.edu (David Sibley)
Subject: Re: Mma bug?
Reply-To: sibley@math.psu.edu
Organization: Dept. of Mathematics, Penn State University
Date: Sun, 12 Apr 1992 18:01:46 GMT

In article 3513@amethyst.math.arizona.edu, zou@.math.arizona.edu (Maorong Zou) writes:
>
>
>
>A possible bug in Resultant[].  
>
>In[1]= f1[x] = 2 h (1-x^2) - (b- g x)^2 - A g^2 (1-x^2) - C x^2(1-x^2)
>
>In[2]= f2[x] = D[f1[x],x]
>
>In[3]= r := Resultant[f1[x],f2[x],x];
>
>In[4]= r/.C->0
>
>Out[4]= 0
>        ^
>        |      
>         which is obviously wrong.
>
>This is Mma 2.0 runing on a NeXT machine.


Obviously wrong? Nope. See Lang's _Algebra_, chapter V, section 10,
"The Resultant". From Lang's treatment, it is quite clear that if you
compute the resultant of polynomials with unknown coefficients and then
plug in values for the coefficients such that the leading coefficients
of the polynomials become 0, then the result is 0. Mathematica has
calculated this correctly.

Indeed, as Proposition 4 in the section of Lang's book cited above
shows, the leading coefficients of the two polynomials are factors of
the resultant. If *either* of these coefficients is later set to 0, the
resultant must be 0 also.

The point is that taking the resultant of polynomials with unknown
coefficients does not commute with evaluating the coefficients. It
makes a difference which you do first in cases where the apparent
degree decreases.


David Sibley
sibley@math.psu.edu
From: avr@cs.purdue.EDU (Andrew V. Royappa)
Newsgroups: sci.math.symbolic
Subject: Re: Grobner basis calculation in MapleV
Date: 16 Apr 92 01:00:13 GMT
Organization: Department of Computer Science, Purdue University


I wrote:
>> 
>> I am trying to implicitize a rational parametric surface. Actually, I'm
>> trying to compute the inversion functions that give the parameters 
>....
>>

Clive writes (sorry, don't know how to include the header):
>I note that -z^2-1+x^2+y^2 is 0 for all (u,v) except at (u,v)=(0,+/-1) and at
>(u,v)=(+/-1,0) where (x,y,z) is undefined.
>
>Clive.


This is quite all right. The parameterization is actually
	x(u,v) = u^2-v^2+1
	y(u,v) = 2*u*v
	z(u,v) = 2*u
	w(u,v) = u^2+v^2-1

giving a point [x,y,z,w] in projective 3-space in terms of a point on
the domain. 

There are two kinds of "undefined": one where w(u,v) = 0; this
includes (u,v) = (+/-1,0) and more generally all points in the domain
where u^2+v^2-1=0 (the unit circle in the domain).

Such points lead to points [a,b,c,0] in projective space ("points at
infinity").

On the other hand at (u,v) = (0,+/-1) you get the tuple [0,0,0,0]
which are not the coordinates of any point. These (u,v) values are
called "base points" of a parameterization, and, all I'll say here is,
if a surface of rational parametric degree 2 has an implicit degree of
2 (as in this case), then it must have two such "base points" (I can
refer interested persons to literature - please see end of message).

This begs the question, "do grobner basis implicitization methods work
in the presence of base points ?" (without major modification)

This is leaving the context of the original discussion, and if it
doesn't belong in sci.math.symbolic, please forgive me.

				Thanks again,

					Andrew

* I found this reference quite readable: "Base Points, Resultants, and
the Implicit Representation of Rational Surface" by Eng-Wee Chionh,
Ph.D. thesis, Department of Computer Science, University of Waterloo,
1990. Dunno if it's been published anywhere.
From: prufrock@athena.mit.edu (Matthew Realff)
Newsgroups: sci.math.symbolic
Subject: Convex and Submodular Functions
Date: 10 Apr 92 22:22:29 GMT
Organization: Massachusetts Institute of Technology

Dear all,

I apologise if this is a FAQ.

Can anyone point me towards any literature on the automatic detection of, and
proof of, convexity or submodularity of functions using symbolic manipulation.

Matthew.