HDTenEightyP/NetNews huggingface dataset:
From: nb@Sunburn.Stanford.EDU (Nancy Blachman)
Subject: The BMUG Math SIG Meeting September 21
Originator: nb@Sunburn.Stanford.EDU
Keywords: Maple, Mathematica, comparison
Organization: Computer Science Department, Stanford University
Distribution: ba
Date: Fri, 21 Aug 1992 20:34:21 GMT

                      Maple V versus Mathematica 2

                               talk by

                            Nancy Blachman
                        Variable Symbols, Inc.

   BMUG Math SIG Meeting at 7 pm on Monday, September 21, 1992

Maple and Mathematica are the two most popular computer algebra
systems on the market today.  Nancy Blachman will share with you
her experience and her opinions on the strengths and limitations 
of Maple and Mathematica. She will answer questions such as:  
How is Maple similar to Mathematica?  In what ways are the 
different? What does Maple offer and who are the primary users 
of Maple? What can Mathematica do and who is using it?  How 
should you decide which system to use/purchase?

Nancy Blachman has been using Mathematica for the past four years.
She is the author of the "Mathematica Quick Reference, Version 2"
(Addison-Wesley and Variable Symbols, 1992) and the tutorial book 
"Mathematica:  A Practical Approach" (Prentice-Hall, 1992).  Recently
she started to use Maple.  She is writing the "Maple V Quick Reference",
a compact guide to Maple V, Release 2.  

This presentation will be at the BMUG office at 2055 Center Street
in Berkeley.  The office is near the north west corner of Center Street
and Shattuck Ave. which is half a block from the Berkeley BART station.

Driving directions:
        Take the University exit off 80.
        Head east on University toward the UC Berkeley campus.
        Turn right at Shattuck (McDonalds will be at the corner.)
        Go 2 blocks.
        Turn right on Center and look for parking.
        I recommend the parking garage on the left, as the one on
                the right closes at 8 pm.

For more information on the Berkeley Macintosh Users Group (BMUG) 
Mathematics Special Interest Group (SIG), contact: 
        Nancy Blachman
        Variable Symbols, Inc
        2161 Shattuck Ave., Suite 202
        Berkeley, CA  94704-1313
        Email: nb@eris.berkeley.edu
        or     nb@cs.stanford.edu
        Fax: 510-843-8702
        Telephone: 510-843-8701
Newsgroups: sci.math.symbolic
From: Richard J. Gaylord <gaylord@ux1.cso.uiuc.edu>
Subject: Re: Mathematica: defining functions. HELP!
X-Xxdate: Sat, 15 Aug 92 09:41:03 GMT
X-Useragent: Nuntius v1.1.1d7
Organization: University of Illinois
Date: Sat, 15 Aug 1992 14:40:50 GMT

Subject: Re: Mathematica: defining functions. HELP!
From: Dave Seaman, ags@seaman.cc.purdue.edu
Date: 14 Aug 92 14:30:59 GMT
In article <56833@mentor.cc.purdue.edu> Dave Seaman,
ags@seaman.cc.purdue.edu writes:
>In article <l8mkk4INN5ll@halcyon.usc.edu> rao@halcyon.usc.edu (Anil Rao)
 
>writes:
>> define a function f(x) = x between x = 2 and x = 5
>>                        = x^2/2 for x < 2
>>                        = 5 x - 20 for x > 5
>> 
>
>At least two methods come to mind. One is to qualify the definitions:
>
>	f[x_] := x /; 2 <= x <= 5
>	f[x_] := x^2/2 /; x < 2
>	f[x_] := 5 x - 20 /; x > 5
>
>and another way is to use a one-liner with nested conditionals:
>
>	f[x_] := If[ x<2, x^2/2, If[ x<=5, x, 5 x - 20]]
>

======================================

a one-liner can be written without nesting 

f[x_] := Which[x<2, x^2/2, x<= 5, x, True, 5x - 20]

comment: note that in the one-liner it is sufficient to use x<=5 because
M goes through Which[..] from left to right, while in the rule-based
method given above, we have to  use 2<=x<=5 so that the rules don't have
overlapping domains because we can't be really sure how M will decide
what rule to use when.
Newsgroups: sci.math.symbolic
From: pete@marsh.cs.curtin.edu.au (Pete Staples)
Subject: Maple question.
Organization: Curtin University of Technology
Date: Mon, 17 Aug 1992 03:56:32 GMT


                                      1/2      1/2
                                    Pi    erf(x    s) ln(lmbda)
  ans :=  limit         exp(x) (1/2 ---------------------------
          s -> infinity                          1/2
                                                x

I am having problems with the following type of expression.

I have written a procedure that uses Laplaces' method to solve integrals.
Maple gives me an integral representation of the answer if I 
enter the limits (s=0..infinity) in the int procedure. If I evaluate
the indefinite integral and use subs for each limit of integration
it still doesn't evaluate the answer, eg leaves it in terms of 
erf(0), erf(x*infinity). Is there anyway that x > 0 can be assumed 
in the expression, so expressions like erf(x*infinity) can be interpreted?

Hope this makes sense, thanks in advance..

Peter.
Newsgroups: sci.math.symbolic
From: caar14@vaxa.strath.ac.uk
Newsgroups: sci.math.symbolic
Subject: Matlab
Date: 13 Aug 92 15:58:58 GMT
Organization: Strathclyde University VAX Cluster

I have heard that a book on MATLAB has been released that is
similar to the one by Wolfram for MAthematica. If this is so
could somebody please e-mail me the details. I've been unable to
find anything in our library or that of several other UK University's
catalogues as well as our University bookshop.

Thanks,
Ronnie.


R.Wallace (caar14@uk.ac.strath.ccsun)
University of Strathclyde,
Mathematics Department,
Livingstone Tower,
GLASGOW,Scotland 
G1 1XH
Newsgroups: sci.math.symbolic
From: ross@ecr.mu.oz.au (Ross McAree)
Subject: Help using Macaulay to convert the tangential equation of a surface into a point equation
Organization: Computer Science, University of Melbourne, Australia
Date: Tue, 18 Aug 1992 03:14:15 GMT



This problem described below is one that I've been struggling with 
for quite a while using maple. Unfortunately  I haven't been able 
to get a result. A couple of people suggested that Macaulay's Grobner
basis computations are most likely to yield a result. This being
so I ftp'd Macaulay, however I find the language of Macaulay
far too mathematical for a mechanical engineer. Can anyone show 
me that way clear through all these "rings" and "ideals" and so 
forth to a possible solution.

The problem is one of converting a quartic envelop surface (QES) in R^3
into a point surface equation.  I suspect that the point surface is a
sextic---certainly a number of sections through it are sextics. The
equation of the QES in terms of tangent plane variables (t, u, v, s) 
is

QES = (a^2 t^4 + b^2 u^4 + c^2 v^4)
	-2 {b c u^2 v^2 + c a v^2 t^2 + a b t^2 u^2 + 2(t^2 + u^2 + v^2)} = 0 

where (t, u, v) is the normal at each plane and s
is the shortest distance of the plane from the origin. The three
"coefficients" a, b, and c are all real and satisfy 

	a + b + c = 0 

In finding a solution to the point equation it would not really 
bother me if I had to substitute in values for a, b, and c, 
though I'd prefer to do it symbolically. 

The "traditional" approach this problem is as follows. If the equation 
of the tangent envelope to the surface is

(*)           F(t, u, v, s)  = 0.

Then the partial derivatives  Ft = dF/dt, Fu = dF/du, Fv = dF/dv, 
and Fs = dF/ds, define the homogeneous point (x, y, z, w):

      x = Ft, 
      y = Fu, 
      z = Fv, 
      w = Fs,

polar to the  general plane (t, u, v, s). If this plane is tangential to 
the surface defined by (*), the polar point (x, y, z, w) is 
on the surface. The equation set defined by the four equations above 
and a further condition (namely the requirement that the point (x, y, z, w)
be on the plane (t, u, v, s)), i.e

(**)	x * t + y * u + z * v + w * s = 0

can be used to find the point equation of  the surface by eliminating
(t, u, v, s). Alternatively the function F could be used instead 
of equation (**) by virtue of Euler's formula for homogeneous
polynomials.

Unfortunately the elimination of t, u, v, s from the equation 
set above has me stumped. It also has maple stumped--I set it 
loose on the problem for two weeks on a sun 4/490
and it didn't get anywhere). Surely this is not a difficult
problem to solve and perhaps someone sufficiently familiar with 
Macaulay could point out how to set up the input file for 
this problem. I believe the script file dual_variety is the likely 
to be required here however I'm totally confused by the 
language of Algebraic geometry and I don't know where to
begin. 

Ross McAree
Robotics Laboratory,
Department of Mechanical Engineering.
The University of Melbourne.
Parkville.
Newsgroups: sci.math.symbolic
From: sherod@newton.Colorado.EDU (Scott Herod)
Subject: Re: Mathematica - Output-Filename
Organization: University of Colorado, Boulder
Date: Thu, 20 Aug 1992 03:20:11 GMT

In article <Bt9FCB.KGn@watserv1.uwaterloo.ca> mrs@.waterloo.edu (M. R. Sridhar) writes:
>
>stream = OpenWrite["filename", FormatType->OutputForm];
>Write[stream, XX, "  ", YY];
>Close[stream];
>
>In the above set of statements how do i make the output filename independent
>of the program? i.e. i would like to specify the output filename before
>these statements are executed. 
>
>Thanks in advance.
>
>Sridhar.
>

In your example "filename" is a string so any one will do.  You can even
create the name interactively by

file = InputString["What file do you want to create?"    ];

Alternately you could send string as a function argument.

dowrite[str_] :=
Block[{stream},
    stream := OpenWrite[strn,....];
    .
    .
]

Hope something like this helps. Feel free to send me mail if you have
a question.

Scott Herod
Applied Mathematics
University of Colorado, Boulder
(sherod@newton.colorado.edu)
From: gaylord@UX1.CSO.UIUC.EDU
Newsgroups: sci.math.symbolic
Subject: translating the APL 'deal' function into M recursively, procedurally and
 functionally - one-liners are faster
Date: 20 Aug 92 10:30:31 GMT

on p.200 in nancy blachman's book, an exercise (#11.4) is given to
translate the APL function 'deal' which randomly selects elements from a
list without replacement into M. it is recommended to do this recursively.

from the manuscript of a text, another person has written the deal function
in M both procedurally and as a recursive rewrite rule and found that the
procedural program runs 4 times faster than the recursive program:

it seems to me that the deal function is an obviously candidate for a
one-liner: here it is:

deal1[lis_List,n_Integer]
:=Complement[lis,Nest[Delete[#,Random[Integer,{1,Length[#]}]]&,lis,n]]

-----------------------------------------------

to clarify what's going on here:

SeedRandom[0]
deal1[Range[9],4]
{2, 5, 6, 7}

we can look at the actual selection process using NestList

SeedRandom[0]
NestList[Delete[#,Random[Integer,{1,Length[#]}]]&,Range[9],4]
{{1, 2, 3, 4, 5, 6, 7, 8, 9}, {1, 2, 3, 4, 5, 6, 8, 9}, 
 
  {1, 2, 3, 4, 5, 8, 9}, {1, 2, 3, 4, 8, 9}, 
 
  {1, 3, 4, 8, 9}}

---------------------------------------------

i ran timing test on the recursive program[deal3], the procedural
program[deal2] and the one-liner program[deal1] with the following results

{Timing[deal1[Range[200],60];],
Timing[deal2[Range[200],60];],
Timing[deal3[Range[200],60];]}
{{0.866667 Second, Null}, {1.01667 Second, Null}, {5.25 Second, Null}}


$RecursionLimit = 1000;


{Timing[deal1[Range[200],200];],
Timing[deal2[Range[200],200];],
Timing[deal3[Range[200],200];]}
{{2.01667 Second, Null}, {2.78333 Second, Null}, {14.3667 Second, Null}}

i can't say that the recursive or the procedural programs (which i did not
write) are the best programs that can be written in those styles but i do
think that the speed of the one-liner confirms the general view that the
more compact the M program and and more built-in M functions that are used,
the faster the code will run. 

richard j. gaylord, university of illinois, gaylord@ux1.cso.uiuc.edu

"if you're not programming functionally, then you must be programming
dysfunctionally"



Newsgroups: sci.math.symbolic
From: tom@steam.uwaterloo.ca (Tom Lee)
Subject: Seeking "Father/Mother" of Computer Algebra
Organization: University of Waterloo
Date: Thu, 20 Aug 1992 14:03:26 GMT


Hello ...

I'm in the process of looking for a speaker (the live kind) for a
gathering on computer algebra, and I would like some assistance and
opinions from the readers of this group.

The basic question is ...

In your opinion, is there a "father/mother" of computer algebra?
That is, is there a person whose vision and/or direction brought about
the development of the first forms of computer algebra (e.g. ALTRAN, 
MACSYMA, etc.)?   

Any information of current affliations of this person and definitive
publications would also be of great assistance.

I will post a summary of responses.


Many thanks in advance.


Tom Lee
Mechanical Engineering
University of Waterloo

tom@steam.uwaterloo.ca

Newsgroups: sci.math.symbolic
From: Tobin C. Anthony <tca712@rs710.gsfc.nasa.gov>
Subject: Control Examples in Mathematica
Organization: NASA-Goddard Space Flight Center
X-Useragent: Nuntius v1.1
Date: Fri, 14 Aug 1992 15:25:20 GMT

I am interested in any packages, functions, or plain old algorithms that
people
have used to solve controls problems in Mathematica.  I am mostly
interested in 
aerospace applications but I would like to see what tools people have
used to solve classical or modern controls problems in any discipline.  I
would like to write my own packages but I am interested in seeing what's
out there.  I would appreciate it if any replies could cc:
amk712@rs710.gsfc.nasa.gov.  Thanks in advance. 

Tobin

----------------------->>>>><<<<<-----------------------
Tobin C. Anthony                   tca712@rs710.gsfc.nasa.gov
Code 712                               301-286-1273 (w)
Goddard Space Flight Center
Greenbelt MD 20771
USA

"Marge, you're just a tool of the dog-house makers" - H. Simpson
----------------------->>>>><<<<<-----------------------
Newsgroups: sci.math.symbolic
From: jake@skatter.usask.ca
Subject: Re: Can anyone solve this?
Organization: University of Saskatchewan
Date: Tue, 18 Aug 1992 02:57:22 GMT




Sorry, but I don't know alot about this new newsreader yet.

I tried:

Integrate[Exp[-b y] Sqrt[x^2 + y^2],{x,a,d}]

in Mma 2.0 and got:

          2    2     2               2    2
-(a Sqrt[a  + y ] + y  Log[a + Sqrt[a  + y ]])
---------------------------------------------- + 
                       b y
                    2 E
 
          2    2     2               2    2
  d Sqrt[d  + y ] + y  Log[d + Sqrt[d  + y ]]
  -------------------------------------------
                       b y
                    2 E

which then Mma choked on for the second integral, which you might find
in tables in chunks.

The other order of integration gets Hankel functions right off the bat.

See Gradshteyn + Ryzhik, page 322.

That's about all I can come up with on short notice.
From: jkc@keller.Mines.Colorado.EDU (Jack K. Cohen)
Newsgroups: sci.math.symbolic
Subject: Re: Mathematica: defining functions. HELP!
Date: 14 Aug 92 15:52:45 GMT
Organization: Colorado School of Mines

In article <l8mkk4INN5ll@halcyon.usc.edu> rao@halcyon.usc.edu (Anil Rao)  
writes:
> 
> ... I want a function to behave 'differently' in different regions.
> How does one do this in Mma?    ...

Here's one I did recently:

MeyerPhiHat[v_, xi_] :=
        Which[
                (* If *)     Abs[xi] <= 1/3, (* then *) 1,
                (* Elseif *) Abs[xi] >= 2/3, (* then *) 0,
                (* Else *)   True,  (* then *) Cos[Pi/2 v[3 Abs[xi] - 1]]
        ]


Another way is to use /; as in:

f[x_] := ...  /; 0 < x < 1
f[x_] := ...  /; 1 <= x
From: drclark@daisy.uwaterloo.ca (David R. Clark)
Newsgroups: sci.math.symbolic
Subject: Re: Maple question.
Date: 17 Aug 92 13:51:23 GMT
Organization: University of Waterloo, Waterloo, Ontario, Canada


   Newsgroups: sci.math.symbolic
   From: pete@marsh.cs.curtin.edu.au (Pete Staples)
   Subject: Maple question.

   ...

   I have written a procedure that uses Laplaces' method to solve integrals.
   Maple gives me an integral representation of the answer if I 
   enter the limits (s=0..infinity) in the int procedure. If I evaluate
   the indefinite integral and use subs for each limit of integration
   it still doesn't evaluate the answer, eg leaves it in terms of 
   erf(0), erf(x*infinity). Is there anyway that x > 0 can be assumed 
   in the expression, so expressions like erf(x*infinity) can be interpreted?

There are a couple of problems here.  The first is that "subs" does not 
attempt to evaluate an expression after performing the substitution.  The
"eval" function can be used to force this evaluation.  This will force
"erf(0)" to 0.  To compute the other endpoint you will have to use the
"limit" function as it will handle erf(x*infinity) as x goes to infinity.
This may well be what you want anyway and is the method used by the
integration routines.

In general, assuming x to be greater than 0 can be done with an assignment
to the signum remember table "signum(x) := 1;" but it will not help in this
case as erf(x*infinity) will still not evaluate.

   Hope this makes sense, thanks in advance..

   Peter.


David Clark
Newsgroups: sci.math.symbolic
From: whitmore@iastate.edu (Kurt D Whitmore)
Subject: Re: MMA on the Mac
Organization: Iowa State University, Ames IA
Date: Fri, 14 Aug 1992 09:28:59 GMT

In <Bs7vG0.CD6@helios.physics.utoronto.ca> butscher@helios.physics.utoronto.ca (Adrian Butscher) writes:

>I use MMA on the Macintosh to handle statistical data (you know how well
>MMA deals with 'list-like' objects), but I have to draw histograms.  I'm
>finding that I don't have very much flexibility in how I present my graphs.
>What I have to do involves some labelling and framing etc. which seems to be
>beyond the scope of MMA.  I have tried doing this in Canvas and Superpaint,
>but I lose the resolution and my graphs print out like bitmaps.

>Are there any suggestions as to how to get around this problem?

>Thanks

>Adrian


This is a problem I have been dealing with over the last 3 years as I make
complex 2 and 3 graphics for textbooks. (Freelance..hint hint).

Though mathematica can do some nice nice graphics if you take the time to program it in, since this is is not very time efficient for high volume graphics I battled with importing graphics in to Canvas, Adobe, Freehand and others and found that none of the formats (Adobe 1.1, EPSF, PS Embedded PICT) gave me the flexibility to make the types of changes to the graph that I wanted to.

So if you would like the solution to this problem please send 5 dollars to...
Just kidding..

I went out and bought DeltaGraph Pro (5 mice in MacUser/World). I save the 
point data in a Mma text file (after replacing the '}, {' with a tab. And any other extraneous curly brackets or other information. Then import tab deliminated data into DeltaGraph. Then you have great control over what your graphic looks like. 

[While I'm here I'd like to mention, I dislike Adobe, it has fallen way behind Freehand and Canvas. I use Canvas as a general purpose package (more bang for the buck) and Freehand when dealing with a lot of bezier curves.]

Look in comp.sys.mac.wanted or comp.sys.mac.apps if you'd like to get some of these programs used, they are much less expensive and sometimes you get a freeupgrade if you happen to hit deadlines just right. I bought DGP and MathType 3.0 (this is the one you can have output to Tex) for 180 bucks altogether. It would have cost me 350+ retail. I even got unregistered copies so I get customer support as well.


Kurt D. Whitmore
whitmore@iastate.edu


Whitmore Technical Publications
1003 N. Hyland
Ames Ia 50010
515 292-3118
Newsgroups: sci.math.symbolic
From: ross@ecr.mu.oz.au (Ross McAree)
Subject: Re: Help using Macaulay to convert the tangential equation of a surface into a point equation
Summary: Error in original post
Organization: Computer Science, University of Melbourne, Australia
Date: Wed, 19 Aug 1992 11:11:35 GMT

In a previous article I wrote 
> 
> The problem is one of converting a quartic envelop surface (QES) in R^3
> into a point surface equation.  I suspect that the point surface is a
> sextic---certainly a number of sections through it are sextics. The
> equation of the QES in terms of tangent plane variables (t, u, v, s) 
> is
> 
> QES = (a^2 t^4 + b^2 u^4 + c^2 v^4)
> 	-2 {b c u^2 v^2 + c a v^2 t^2 + a b t^2 u^2 + 2(t^2 + u^2 + v^2)} = 0 
> 

There is a slight error in this equation. It should read:

QES = (a^2 t^4 + b^2 u^4 + c^2 v^4)
       -2 {b c u^2 v^2 + c a v^2 t^2 + a b t^2 u^2 + 2(t^2 + u^2 + v^2)s^2} = 0
						         missing term--^				

Ross.

Newsgroups: sci.math.symbolic
From: Ray Zimmerman <Ray-Zimmerman@cornell.edu>
Subject: Re: mathematica question- using complex symbols
X-Xxdate: Wed, 12 Aug 92 15: 42:58 GMT
Nntp-Posting-User: rz10@cornell.edu
Organization: Electrical Engineering, Cornell University
X-Useragent: Nuntius v1.1.1d7
Date: Wed, 12 Aug 1992 14:41:18 GMT

mathematica question- using complex symbols

In article <1992Aug11.202102.14808@athena.mit.edu> Saurav D Bhatta,
bhattas@athena.mit.edu writes:
>I have been trying to manipulate complex symbols
>					 ^^^^^^^^ 
>(as opposed to complex numbers) using mathematica.  I had expected
>mathematica to be able to simplify expressions containing complex
>symbols the same way it simplifies complex number expressions.
>for example, if we do     z= 3+ 4 I    , and then compute 
>z*Conjugate[z], the answer output will be 25. but on the other hand,
>if we do      z=x + I y    and then compute z*Conjugate[z], mathematica,
>instead of giving the desired answer x^2 + y^2, outputs something like
>(I x + y)*Conjugate(I x + y). i.e. it refuses to simplify the complex
>expression.
>
>i am wondering if it is possible to get around this problem. i am going
>to to be using long expressions containing many complex symbols, and
would 
>like to get the final answer as a sum of one real part and one imaginary
>part. i am a relatively inexperienced user of this software (and am
using it
>only for some very specific purposes)- so any suggestion will be greatly
>appreciated. thanks.
>
>
>saurav bhatta
>(bhattas@presto.mit.edu)

If you've got Mathematica 2.0 or later try using the built in function
ComplexExpand[].  It doesn't solve all the problems but I found it to
be somewhat useful when trying to do the same thing on some very
complicated expressions.  Note that after using ComplexExpand[] you
can't just use Re[] and Im[] to pick off the real and imaginary parts
although you can probably use the Part[] function to pick off those
parts of the resulting expression.  That's what I ended up doing.
(which, by the way, certainly doesn't mean it's the best solution)
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Ray Zimmerman                         Ray-Zimmerman@cornell.edu  ::
::..................................................................::
::  THIS SPACE FOR RENT. THIS SPACE FOR RENT. THIS SPACE FOR RENT.  ::
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
From: jkc@keller.Mines.Colorado.EDU (Jack K. Cohen)
Newsgroups: sci.math.symbolic
Subject: Calc Help file for Mma/NeXT
Date: 14 Aug 92 22:34:54 GMT
Organization: Colorado School of Mines

My colleague, Frank Hagin, has written a file
for teaching Freshman Calculus students how to
run Mathematica on a NeXT.  Eg. how to use a
mouse, scroll, run simple commands, edit, etc.

It's available with our other Calculus materials
via anonymous ftp  (in pub/papers) at:
hilbert.mines.colorado.edu
or
138.67.12.63