MathUser

Winter 1994

Contents

Mathematica Applications Library
How to Get the X Front End
Electronic Publishing with MathSource
Feature Focus: Customizing Mathematica with init.m

Mathematica Days: More to Come

Over a thousand people attended the five Mathematica Days held earlier this  fall in the United States and Europe. The Mathematica Days were intended for new Mathematica users and other people interested in Mathematica. The Days focused on elementary and intermediate tutorials, covering introductory Mathematica programming, graphics, notebooks, and MathLink. Attendees also received practical information from fellow Mathematica users in the areas of engineering, finance, and education. A special highlight was that each day opened with a talk by Stephen Wolfram, entitled Mathematica and the Future of Technical Computing.
    
Attendees said that they now feel better equipped to apply Mathematica to daily projects to enhance their productivity. Laurie Iten, a professor of biological sciences at Purdue University, said, "I wanted to see how other people are using the program and I did. I'm looking forward to incorporating Mathematica into my research."

Mathematica Days attendees told us that their colleagues are also interested in learning more about Mathematica. When asked what is the best way for their colleagues to learn about Mathematica, they responded, "Attend a Mathematica Day." 

Positive feedback from those who attended, and requests  from others who weren't able to make it, have encouraged us to hold future Mathematica Days in more locations throughout the world. If you or someone you know would like to receive information about future Mathematica Days near you, call Wolfram Research or send us an email message to mdays@wri.com to add your name to our mailing list. As soon as dates and locations for future Days are scheduled, we will mail a brochure and registration form to you.

Lecture Tour In Japan

Because of the success of the Mathematica Days, we have scheduled a series of "mini" Mathematica Days for late January 1994 throughout Japan. Keep an eye out--more information will be sent to local Mathematica users soon.

Selected Tutorial Notes

Mathematica Days attendees also had the opportunity to buy the new Wolfram Research publication, Selected Tutorial Notes, a collection  of tutorial notes from previous conferences. If you are a new user, the Selected Tutorial Notes are a great way to get started with Mathematica. To order a copy of the Selected Tutorial Notes, call 217-398-0700. (In Europe call +44-(0)993-883400).

New Applications Library Set to Release

Professionals use Mathematica's numerical, symbolic, graphics, and programming capabilities to solve problems in their fields every day. To make it even easier for professionals to incorporate Mathematica in different areas, Wolfram Research has introduced the Mathematica Applications Library. The Applications Library supplements tools that Mathematica already contains with profession-specific notebooks and packages. The notebooks contain examples that show and describe specific techniques for using Mthematica. The packages predefine common algorithms and formulas used in various fields.

The first two available volumes of the Applications Library are the Electrical Engineering Pack and the Finance Pack. These volumes can be used in many ways and provide users with 

- ready-to-use Mathematica functions
- introductory tutorials on a given topic
- examples of Mathematica programming
- a core for user algorithms
- ideas for project documentation in notebook format

Electrical Engineering Pack

The Electrical Engineering Pack is a collection of notebooks and packages that cover electrical engineering problems, ranging from elementary to advanced topics. Examples, drawn from circuit analysis, transmission line theory, and antenna analysis, show how to use Mathematica in electrical engineering.  

The Electrical Engineering Pack includes examples from:
Mesh Circuit Analysis
Nodal Circuit Analysis
Bode Plots
Laplace Transforms
Circuit Sensitivity Analysis
Ideal Diode and Bipolar Transistor Models
Chaotic Behavior in a Nonlinear Circuit
Passive Component Noise
Amplifier Noise Figure
Harmonic Distortion
Crossover Distortion
Clipping Distortion
Resistor Selection
Y to S Parameter Conversion
Project Documentation
Symbolic Derivation of Transmission Line Parameters
Analysis of Reflections Using Animations
Suppression of Line Ringing by Lossy Lines
Matrix Techniques for Microwave Transmission Line Analysis
Dispersion in Uniform Microstrip Lines
Smith Chart Design Tools

Finance Pack

The Mathematica Finance Pack is designed for traders, investment analysts, portfolio managers, and others in the financial community who want to use Mathematica to analyze financial data and design strategies. Individual investors, as well as research staff from small brokerage houses to large financial institutions, will find this toolkit valuable. 

Topics covered in the Finance Pack include interest rates, bonds, general cash flow, options, and finance calendar computations. The specialized tools cover term structure of interest rates and all commonly used sensitivity functions needed for risk management.. 

The Finance Pack includes:
Flat Constant Rates
Term Structure of Interest Rates
Spot Rates
Forward Rates
Discount Factors
Interest Rates Conversion
Simple Representation of Interest Rates
Bonds
Simple Representation of Cash Flows
Options
Finance Calendar Computations
Random Number Generation
Markowitz Efficient Portfolio
Betas and Security-Market Line
Moving Averages

How to Order a Library Volume

Order a volume and start increasing your productivity today. For a limited time, Wolfram Research is offering the Electrical Engineering Pack at an introductory price of $99 (regularly $195). This offer ends January 31, 1994. The Finance Pack is available for $395. Both volumes run on Microsoft Windows, Macintosh, and Unix. To order, contact us at 217-398-0700. (In Europe, call +44-(0)993-883400.)

How to Get the X Front End

Shipments of the Mathematica X front end recently began for Sun SPARC-based systems (under Sun OS 4.1), Silicon Graphics, Hewlett-Packard 700 Series, DEC MIPS, Sun Solaris (2.0 or higher), and IBM RISC System/6000 computers, providing notebooks, a function browser, and on-line help to Unix users. Mathematica notebooks are interactive documents in which a user can combine text, calculations, and graphics. Notebooks are also transferable between platformsÐa notebook created on a Unix machine, for example, can be used on a Macintosh, or vice versa.

How can you get the notebook front end on your workstation as soon as possible? The answer is Mathematica Plus, the automatic customer update program for Mathematica. If you have bought a subscription to Mathematica Plus for one of the six platforms listed above, you will automatically receive a complimentary X Front End Update Kit. This kit is not considered one of the two updates regularly provided under the Mathematica Plus program, so you can expect to receive two other updates in addition to this kit. (Please note that you are only eligible to receive the update kit if you bought a full Mathematica Plus subscription.)

If you haven't yet purchased a subscription to Mathematica Plus for one of the platforms mentioned above, you can still subscribe by December 31, 1993 to receive your complimentary X Front End Update Kit and two additional Mathematica updates as soon as they are released.
 
To subscribe to Mathematica Plus, contact Wolfram Research at 217-398-0700 or send email to info@wri.com. In Europe, call +44-(0)993-883400 or send email to info-euro@wri.com.

New Versions

NEXTSTEP for Intel

Mathematica 2.2 is now available for NEXTSTEP, NeXT's object-oriented software for Intel-486 and Pentium-based computers, including COMPAQ Deskpro L, Dell ME, Gateway V, IBM ValuePoint 466DX2/D, and Zenith Z-Station XEn computers. The NEXTSTEP version is identical to Mathematica for the NeXT and compatible with all other notebook front end versions.

X Window System

The X notebook front end is currently shipping for Sun SPARC-based systems (under Sun OS 4.1), Silicon Graphics, Hewlett-Packard 700 Series, DEC RISC, Sun Solaris (under 2.0 or higher), and IBM RISC System/6000 computers. The X front end is compatible with other notebook versions and runs under Motif.

OS/2

A native OS/2 port of the Mathematica kernel is in testing. It will be available soon and will feature full 32-bit addressing. (Currently, Mathematica for Microsoft Windows runs under OS/2v2.1. Mathematica Version 2.2 for MS-DOS runs under OS/2v2.0.)

Windows NT

A Mathematica version for Windows NT is also in testing and will feature both a 32-bit kernel and a 32-bit front end. Mathematica for Windows NT will also be compatible with Windows 3.1.

MathLink Developer Kit for Microsoft Windows

MathLink for Windows is currently in testing. It is expected to ship after the first of the new year, enabling Microsoft Windows users to link Mathematica to external programs, such as Microsoft Excel or a remote kernel or front end from other Mathematica platforms. 

MathLink for Microsoft Windows is a DLL (dynamic link library) that can be used from any Windows development environment that supports DLLs. With the MathLink Developer Kit, many kinds of programs can be adapted to exchange data and commands with Mathematica. The kit includes MathLink documentation and sample MathLink applications: a small Mathematica front end and programs written in C and Visual Basic.

Registered users of Mathematica 2.2 can get the MathLink Developer Kit for Microsoft Windows by calling Wolfram Research. You can also request the kit by email at orders@wri.com. (In Europe, send mail to info-euro@wri.com.) Be sure to include your postal address and Mathematica license number.

Special Functions with Mathematica

Of the infinite number of mathematical functions that exist, only several hundred have been given names. Everyone knows about the "elementary" functions: circular and hyperbolic trigonometric functions, the exponential function, their inverses, and polynomial functions. All other functions are considered "special" functions.
 
There are several broad classes of special functions, including the special functions of mathematical physics, elliptic integrals, and integrals of elementary functions. Mathematica contains the most important special functions in these and other classes. For example, Mathematica has groups of Bessel and elliptic functions, as well as the Gamma and Zeta functions. 

Mathematica has several principles that apply to the evaluation of mathematical functions:

- Mathematica algorithms evaluate each function throughout the complex plane to any precision.

- When given a machine number as an argument, Mathematica attempts to return the machine number closest to the value of the function at that argument.

- Mathematica's interface is designed to make it easy to use special functions as building blocks of other functions.

- Mathematica's algorithms are designed to be efficient and well-conditioned (i.e., insensitive to errors either in the arguments to the function or in values intermediate in the calculation).

In addition, Mathematica uses meta-algorithms to select the best of several algorithms for any particular set of parameters. For example, if the best algorithm for evaluating e^x were the series expansion, Mathematica would distinguish between the cases x<0 and x>0. The series expansion at x = -12.0 suffers from catastrophic cancellation of digits: 1 - 12. + 72. - 288. + ... + 17062.8 - 18613.9 + 18613.9 - 17182.1..., but e^(-x)=1/(e^x) and 1/(1 + 12. + 72. + 288. + ...) involves no cancellation. 

Occasionally all algorithms are more ill-conditioned than the function itself, and digits will be lost in cancellation. Mathematica's arbitrary-precision arithmetic monitors the precision of the calculation to know how many extra digits are needed when reevaluating the function with higher precision. Mathematica automatically reevaluates the function with higher precision to compensate for any ill-conditioning of the algorithm in excess of the ill-conditioning of the function. However, when the function itself is ill-conditioned, the algorithm does not give more digits than justified by the function.

For more information about special functions in Mathematica, see Section 3.2.10 of Stephen Wolfram's book, Mathematica: A System for Doing Mathematics by Computer, Second Edition.

Examples

The closest machine number to erf(10) is 1.

Erf[ N[10] ]

Considerably more than 20 digits are justified by a 20-digit
approximation to erf(10).

Erf[ N[10, 20] ]

Log[Gamma[z]] restricts the imaginary part to be between -Pi and Pi and results in the complex plane being cut by infinitely many curved branch cuts. By analytic continuation, LogGamma[z] just has a branch cut along the negative real axis.

LogGamma[ 2.3 + 8.9I ]

The Airy Ai function is related to Bessel functions of order 1/3. The Airy Ai function can be used to describe the probability of finding a quantum particle, such as an electron, at various distances from a linear potential barrier.

Plot[ AiryAi[x], {x, -10, 5} ];

Riemann's Zeta function can be evaluated anywhere in the complex plane. This is near the first zero on the critical line with an imaginary part greater than 1000. The precision of the result is only as high as justified by the input.

Zeta[ 1/2 + 1001.3494826377827371221033 I]

JacobiSN[ ] is an elliptic function related to the motion of a simple pendulum. When x is near 1, the function corresponds to a pendulum that swings almost from vertical to vertical, nearly balancing at each end of the swing.

Plot[ JacobiSN[x, .99], {x, 0, 15} ];

Updating User Registration Information

Keeping your registration information up to date helps us manage license information more efficiently, issue passwords faster, and send update and new product information. Please take a moment to check the name and address on the mailing label of this issue of MathUser. (Note
that we send MathUser, update information, and all other Mathematica mailings to the same address.) An R after your name indicates that you are a registered user. An N after your name indicates that you are a MathUser subscriber, but not a registered user.

Please contact User Services if
- the address information is incorrect
- you are a registered user, but do not have an R code
- the person on the label is no longer with your organization, or
- you receive more than one copy of MathUser

You can reach User Services by fax at 217-398-0747 or by email at register@wri.com. As always, we welcome your comments and suggestions.

Starting a Mathematica User Group? Wolfram Research Can Help.

User groups help spread Mathematica news and knowledge. Wolfram Research supports Mathematica user groups with materials, information, and promotion. If you would like to join or start a Mathematica user group, we can put you in contact with other interested users. For information about Mathematica user groups, contact the User Group Administrator at mug@wri.com. (In Europe, send email to mug-euro@wri.com.)

Electronic Publishing with MathSource

As more books are supplemented with Mathematica packages and notebooks, authors and publishers need a convenient, effective way to publish electronically. The best way to publish electronic supplements, periodicals, and documentation is with MathSource, the electronic resource for Mathematica-related materials.

Here are some of the important advantages of publishing with MathSource.

- MathSource reaches Mathematica users around the world, averaging 2000 sessions weekly from over 50 countries.

- MathSource is accessible by email, direct dialup, anonymous ftp, and Gopher.

- MathSource sends materials in formats appropriate for different computer systems, making it unnecessary for publishers to make different versions of supplements. MathSource can send files formatted for Macintosh, DOS, and Unix computers, and also send NeXTmail.

- Users can search MathSource by keyword to easily find all Mathematica materials on a topic.

- Authors and publishers save the production cost of packaging disks with books.

- To distribute a new version or bug fix, an author has only to submit updated materials to MathSource, instead of mailing disks to each person who bought the book. MathSource can automatically notify users when an author updates materials, ensuring that everyone has the most current version.

How to Publish with MathSource

Do you have materials that you would like to publish with MathSource? You can send us the materials via email, on disk, or give the address of an anonymous ftp site. When submitting materials to MathSource, be sure to include the title of the material, an abstract, suggested
keywords, and who to contact for more information about the materials.

If you would like more information about publishing Mathematica-related materials with MathSource, send email to the MathSource administrator at ms-admin@wri.com, or call 217-398-0700.

A Sample Email Session with MathSource

In addition to Find and Send, MathSource has commands that you can use to indicate your file format preference, tell MathSource whether or not it should compress files before sending, and modify search parameters. Here is a sample email session that shows how you can search for and download MathSource materials.

Find Request to MathSource

If you indicate your computer type,                      To: mathsource@wri.com
MathSource can pick an appropriate 
compression scheme and put correct 
end-of-line characters in files.                               System Macintosh	

This tells MathSource to return            Format Notebook
the results of the Find command in
a Mathematica notebook. 

This sets 100K to be the maximum                       MaxKBytes 100 
mail message size that MathSource 
sends to you. 

This returns a list of the items                              Find "Programming in 
whose titles and summaries                                      Mathematica"
contain the string "Programming in				
Mathematica".

MathSource Reply

In response to the Find request,                           [ picture not shown ]
MatSource sends this notebook. In 
addition to notebooks, you can 
instruct MathSource to send Find 
results in  PostScript, TeX, or 
ASCII files.

Send Request to MathSource

This requests item 0205-186.                                To: mathsource@wri.com
	                            Send 0205-186

This searches for all submissions                          Find Organization: Wolfram 
from Wolfram Research.                                             Research

This indicates that the remainder                           Operator
of your message should be read by                        Please send me more infor-	
a human operator.                                                   mation about submitting
                                                                                materials to MathSource.

For more detailed descriptions of these and other features, download the MathSource Technical Report, item 0202-554.

Two Ways to Get a Faster Response from MathSource

1. Send each Find command in a separate message. Because MathSource processes your entire message before returning a response, a single  message containing several Find commands can take longer than several messages with one Find command each.

2. Send MathSource as few keywords as possible for each item. For example, to find information on modified Bessel functions, send the command Find Bessel instead of Find Modified Bessel Function. Because MathSource does a full search for each keyword in your message, sending one keyword for an item will get results faster than several keywords.

A Few Electronic Supplements Now on MathSource

- The Mathematica Journal
- Mathematica in Action 
- Programming in Mathematica 
- Economic and Financial Modeling with Mathematica
- Partial Differential Equations with Mathematica
- Simulating Neural Nets with Mathematica
- Mathematica in Education
- Applied Mathematica: Getting Started, Getting It Done
- Introduction to Programming with Mathematica

WRILaTeX

Authors writing books or technical reports based on Mathematica can get the WRILaTeX document system from Wolfram Research. The WRILaTeX document system was used to produce Stephen Wolfram's  Mathematica: A System for Doing Mathematics by Computer, and other Mathematica documentation. WRILaTeX consists of LaTeX style files, macro definitions files, and other utilities that make it easy for authors to incorporate Mathematica input and output into a TeX-based document. For information about WRILaTeX, send email to wrilatex@wri.com.

New Books

These new Mathematica books range from introductory tutorials in programming, mathematics, and Mathematica, to specialized professional reference books. For information, contact the publishers or any technical bookstore.

English Titles

Applied Mathematica: Getting Started, Getting It Done
William T. Shaw and Jason Tigg (Addison-Wesley, ISBN 0-201-54217-X)

Shows how to solve complex, practical problems in engineering, finance, environmental engineering, and image processing. Provides a quick start for scientists and engineers. Electronic accompanying materials are available on MathSource.


Calculus Using Mathematica
K.D. Stroyan (Academic Press)
ISBN 0-12-672971-9 (with Macintosh disks)
ISBN 0-12-672972-7 (with IBM/DOS disks)
ISBN 0-12-672973-5 (with NeXT disks) 

Textbook for three-semester undergraduate calculus. Fully integrates Mathematica into the primary text and comes with Mathematica notebooks on disk.


Scientific Projects and Mathematical Background for Calculus Using Mathematica
K.D. Stroyan (Academic Press, ISBN 0-12-672975-1)

A companion workbook to Calculus Using Mathematica.


Introduction to Computer Performance Analysis with Mathematica
Arnold Allen (Academic Press, ISBN 0-12-051070-7)

Beginner's guide to computer performance analysis. Topics include benchmarking, measurement requirements, simulation, and forecasting. Comes with Mathematica files on disk.


Introduction to Programming with Mathematica
Richard J. Gaylord, Sam N. Kamin, and Paul R. Wellin
(TELOS/Springer-Verlag, ISBN 0-387-94048-0)

A textbook introducing programming in the Mathematica language. Emphasizes the functional and rule-based styles unique to the Mathematica programming language. Does not assume prior programming or Mathematica experience. Comes with electronic supplement.


Simulating Neural Networks with Mathematica
James A. Freeman (Addison-Wesley, ISBN 0-201-56629-X)

Introduces the operations and application of neural networks in the context of Mathematica's programming language. Shows professionals and students how to use Mathematica to simulate neural network operations to assess neural network behavior and importance. Electronic materials available on MathSource.

Non-English Titles

Erste Schritte mit Mathematica [First Steps in Mathematica]
W. Burkhardt (Springer-Verlag, ISBN 3-540-56650-3)

An introduction to Mathematica designed for independent study or introductory courses. Emphasizes the most important areas of application through the use of problems in high school and university mathematics.(in German)


Informatik fur Mathematiker und Naturwissenschaftler: Eine Einfuhrung mit Mathematica  [Computer Science for Mathematicians and Scientists: An Introduction with Mathematica]
Roman Maeder (Addison-Wesley, ISBN 3-89319-519-X)

A textbook for introductory computer science, especially for mathematicians, scientists, and engineers. Treats traditional computer science topics and shows how modern computer-based tools can be used to do scientific computation. (in German)


Mathematica: Ein systematisches Lehrbuch mit Anwendungsbeispielen [Mathematica: A Comprehensive Guidebook with Practical Examples]
Ernst H.K. Stelzer (Addison-Wesley Deutschland, ISBN 3-89319-495-9)

Introduction to Mathematica with applications based on problems taken from physics, chemistry, and biology. Special emphasis on analysis, linear algebra, and numerical mathematics. (in German)

Translations

Mathematica griffbereit, Version 2 [Mathematica: Quick Reference, Version 2]
Nancy Blachman (Verlag Vieweg, ISBN 3-528-06524-9) (in German)

Mathematica in Aktion [Mathematica in Action]
Stan Wagon (Spektrum Akademischer Verlag, ISBN 3-86025-041-8) (in
German)

Forthcoming Books

These books will be available in early 1994.

Animating Calculus
Ed Packel and Stan Wagon (W.H. Freeman, ISBN 0-7167-2428-6)

A supplement for first-year calculus. Contains a series of 22 Mathematica notebooks exploring topics in calculus of a single variable.

Grafik mit Mathematica [Graphics with Mathematica]
Ralf Schaper (Addison-Wesley Deustchland, ISBN 3-89319-612-9)

Mastering Mathematica: Programming Methods and Applications
John Gray (Academic Press Professional, ISBN 0-12-296040-8)

Discusses functional, rule-based, procedural, and object-oriented programming with Mathematica. Also covers graphics programming and writing Mathematica packages. Comes with electronic supplement.


The Mathematica Programmer
Roman Maeder (Academic Press Professional, ISBN 0-12-464990-4)

Covers the use of Mathematica as a programming language. Topics include object-oriented programming, abstract data type design, relational databases, minimal surfaces, and fractal curves. Comes with electronic supplement.


Revised Edition of Mathematica by Example
Martha Abell and Jim Braselton (Academic Press Professional, ISBN0-12-041530-5)

Compatible with Mathematica Version 2.2 and shows fundamental Mathematica techniques for the beginning user. Topics covered include calculus, linear algebra, differential equations, and discrete mathematics.


Quantum Methods with Mathematica
James M. Feagin (TELOS/Springer-Verlag, ISBN 0-201-58221-X)

For students and experienced professionals who would like to explore quantum physics using Mathematica. Divided into two parts: Systems in One Dimension, and Quantum Dynamics. Comes with an electronic supplement.

Other Mathematica Books

In addition to these books, which feature special topics with Mathematica, there are many books that come with Mathematica supplements. In the next issue of MathUser, we will list books that use Mathematica. If you have written a book that comes with a Mathematica supplement, please tell us about it by sending email to mathuser@wri.com, or fax to 217-398-0747.

Opportunities at Wolfram Research

Wolfram Research is expanding and we are looking for outstanding people to join our team. Positions are open in research and development, technical writing, and technical marketing. Send applications for all positions to Personnel department, Wolfram Research (resumes@wri.com).

Wolfram Research is an affirmative action/equal opportunity employer.

Feature Focus

Customizing Mathematica with init.m

You can customize your version of Mathematica by changing init.m, an initialization file loaded when Mathematica starts up. By writing a new init.m file, or changing the default init.m, you can set Mathematica to

- prompt users for different option settings while the kernel is launching 
- automatically load packages and launch MathLink applications you use every day instead of      manually loading them
- print a message as Mathematica starts up; for example, a network administrator might add a    Print statement to init.m that users will see when starting the network copy of Mathematica  

Consider a few things when writing init.m files:
- If you are using Mathematica on a network, it is best to create an additional init.m file for your home directory instead of changing the network default init.m. However, it is possible to load both the custom and default init.m files.
- If you are the only user of a copy of Mathematica you may prefer to modify the default init.m. However, be careful when removing commands from the default init.m.
- The directory in which you place a custom init.m will vary with each platform because packages and files are stored differently from platform to platform.

For more information about writing a custom init.m file or loading multiple init.m files, see "Customizing Mathematica with init.m" available from MathSource, item 0205-838.

A Sample Custom init.m

This tells a user that                                    Print[""];
Mathematica is loading a                            Print["Running Mathematics 
custom init.m.                             Department custom init.m..."]

This automatically loads                             Print["Loading Graphics`Animation` 
Graphics`Animation`and                     and Graphics`Graphics`..."] 
Graphics`Graphics`.                      <<Graphics`Animation`;
                            <<Graphics`Graphics`;
                               
This asks the user whether          If[ MatchQ[ InputString["Load 
or not to load                                                   Geometry`Polytopes`? 
Geometry`Polytopes`.                         Y/N (default = no):"],
                                                                   "y" | "Y" | "yes" | "Yes" | "YES"],
    		                  <<Geometry`Polytopes`];

This prompts the user for                            SetOptions[$Output, PageWidth -> 
a page width value.                                     Input["Enter the Page Width
                                (Number of Characters):"] ]

This installs the MathLink                           Install["mlprogram"]
application mlprogram.

This is a message to users               Print[ "An electronic version of             from the network administrator.                 'New Features in \n Version 2.2'
                                                   is in /Documentation."]

On Unix platforms, this loads           Block[{$Path = 
the default init.m file.               DeleteCases[$Path, "." | "~"]},
                                 Get["init.m"]]

Here's how this custom init.m will start up Mathematica:

server[1]> math
Mathematica 2.2 for NeXT
Copyright 1988-93 Wolfram Research, Inc.

Running Mathematics Department custom init.m...
Loading Graphics`Animation` and Graphics`Graphics`...
Load Geometry`Polytopes`?  Y/N (default = no):n
Enter the Page Width (Number of Characters):60
An electronic version of 'New Features in 
 Version 2.2' is in /Documentation.

In[1]:= 2 + 2

Out[1]= 4

Q&A

Q: How can I combine a surface plot (with axes labels and ticks) with a Text graphic using Show? I tried to do this but my plot contains only the surface plot and the text.

A: When Show receives a number of graphics objects as input, it converts them to the same type of graphics object. For example, if you combine a SurfaceGraphics object with a two-dimensional graphics object, Mathematica converts the SurfaceGraphics object to a Graphics object. Mathematica only converts the primitives of the SurfaceGraphics object and not the options, consequently losing the axes and labels. The simple way to keep the axes and labels is to render everything as a three-dimensional object. Here's an example:

surface = Plot3D[Log[Cos[y]/Cos[x]], {x,-1,1}, {y,-1,1},
            BoxRatios->{1,1,.5}, DefaultFont->{"Times-Italic", 10},
            AxesLabel->{"x","y","z"}, Mesh->False];

Show[ {surface, Graphics3D[Text["saddle point", {0,0,.1}]]} ];

Using the Show command, surface, a three-dimensional object, is combined with a Graphics3D object, so the axes and labels are kept.

Q: I have a lab of 100 Macintosh computers. I'd like to be able to run Mathematica from any 50 of the computers at the same time. How can I do this?

A: A network license enables you to do this. You can buy a network license for the number of copies you would like to run simultaneously and run Mathematica from either a network server or from each individual machine.

You have three options for installing and running Mathematica under a network license.

- Install Mathematica on each machine covered by the license. This requires that you install the network license password on each machine. Mathematica usually runs fastest when installed on each  machine.

- Install Mathematica on a file server, start it up, and enter the password when Mathematica asks for it. Then copy Mathematica to each machine. Before copying Mathematica from the file server, move "Mathematica Kernel Prefs" from the Preferences folder (in the System folder) to the Mathematica folder. "Mathematica Kernel Prefs" is a file that contains password information. By copying this file along with Mathematica, you will not need to type the password on each machine.

- Install Mathematica on a file server and run it across the network. This is the easiest way to install Mathematica. However, Mathematica runs more slowly across a network than it does on a single machine. (Mathematica will alert you if you attempt to start up Mathematica when all copies are already in use.)

After installing Mathematica on the server:
1. Launch Mathematica and type in the network license password.
2. Quit Mathematica.
3. Move "Mathematica Kernel Prefs" from the Preferences folder to the folder containing "Mathematica Kernel".

You can now launch Mathematica from any machine connected to the server.

Mathematica Developer Conference for Advanced Users Scheduled for Spring 1994

The Mathematica Developer Conference is scheduled for April 21-23, 1994 at the Wolfram Research headquarters in Champaign, Illinois. The conference will give advanced users an opportunity to meet Wolfram Research staff and other Mathematica experts to share ideas and experiences. The Developer Conference will feature workshops, panels, luncheons, a computer lab, and a series of informative, practical sessions. A major focus of this conference will be to help users create Mathematica packages, MathLink applications, Mathematica books, and interactive texts.

If you are interested in attending the 1994 Mathematica Developer Conference, send your name and address by email to conference@wri.com, or by fax to 217-398-0747.

About MathUser

MathUser is published by Wolfram Research to provide news and information about Mathematica to registered Mathematica users. MathUser is also available free of charge to other people interested in Mathematica. To be added to the list of subscribers or to submit a change of address, send your postal address information to mathuser@wri.com, or call 217-398-5151. (In Europe, fax +44-(0)993-883800.) Note that MathUser is sent to your registration address, the same address where all other Mathematica information and mailings are sent.

Electronic copies of back issues of MathUser are available on MathSource. This issue of MathUser is MathSource item 0205-771. For paper copies of back issues, send an email request to mathuser@wri.com.

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On the Cover

The cover shows a collection of polyhedra created with Graphics`Polyhedra`. The set of commands used to generate the polyhedra is available as a subitem of MathSource item 0205-771.

Wolfram Research, Inc., 1993. MathUser (ISSN 1062-7030) is published quarterly by Wolfram Research, Inc., 100 Trade Center Drive, Champaign, IL 61820-7237, USA; email: mathuser@wri.com.

Mathematica, MathLink, and MathSource are registered trademarks, and MathUser is a trademark of Wolfram Research, Inc. Mathematica is not associated with Mathematica Inc., Mathematica Policy Research, Inc., or MathTech, Inc. All other product names mentioned are trademarks of their producers.