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Newsletter: Math Forum Internet News No. 5.30 (24 July 2000)
Posted:
Jul 21, 2000 8:47 PM


To our subscribers:
We'd like to thank those of you who have reported receiving duplicate newsletters. Staff members are also getting two copies, so we're aware of the problem and our syadmins are trying to figure it out. Not all subscribers are getting duplicates, which complicates troubleshooting, and a major listserv upgrade is planned for next week; we hope this will resolve the situation.
To ease your email load, our July discussion group issue will be combined with the August issue and sent to you next month. Thank you all for your patience, and we will continue to work on this problem.
 Sarah
24 July 2000 Vol. 5, No. 30
THE MATH FORUM INTERNET NEWS
Zero Saga & Confusions with Numbers  Arsham DPGraph  Parker  Fly & Trains  Dr. Math FAQ
THE ZERO SAGA & CONFUSIONS WITH NUMBERS Prof. Hossein Arsham; University of Baltimore
http://ubmail.ubalt.edu/~harsham/zero/ZERO.HTM
A critical panoramic view of basic mathematical fallacies surrounding zero, such as:
 dividing by zero  taking the limit  IEEE special floating point  the notion of zero throughout history  when zero is "not there"  the origin of infinity and its symbol  taking the square root of both sides of an equality  manipulation on divergent series  taking conventions for proofs  taking the derivative with respect to a discrete variable  misplacement of the sign (square root)  confusion between a number and an operation, and  "errant views"
Notes, further readings, and references are included.
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DPGRAPH  David Parker Dynamic Photorealistic Graphing
http://www.davidparker.com/
Written in assembly language, DPGraph runs under Windows and Windows emulators. The software allows you to:
 display multiple simultaneous dynamic photorealistic 3D implicit equalities and inequalities, and intersections of their volumes;  spin, slice, and view timedependent (moving) photorealistic surfaces in real time; and  construct 2D, 3D, 4D, 5D, 6D, and 7D graphs (as an example of a 7D graph, DPGraph can do 3D arrays of timedependent 3D vectors, i.e., dynamic vector fields).
Information on site licensing and costs, software reviews, technical support and FAQs, upgrades, and a library of graphs, movies, and links are available onsite.
http://www.davidparker.com/library.html
The June issue of Visual Mathematics featured a gallery devoted to DPGraph, with graphs created by mathematicians and scientists from around the world, including three high school students and one junior high school student. The credits for the graphs are at the end of the gallery.
http://members.tripod.com/vismath3/parker/gr.htm http://members.tripod.com/vismath3/parker/gr5.htm
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New from the Dr. Math FAQ
FLYING BETWEEN TWO TRAINS
http://mathforum.com/dr.math/faq/faq.fly.trains.html
Two trains 150 miles apart travel toward each other along the same track, the first train at 60 miles per hour, the second at 90 miles per hour. A fly buzzes back and forth between the two trains until they collide. If the fly's speed is 120 miles per hour, how far will it travel?
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The Math Forum ** 24 July 2000
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