Math Forum Internet News

Volume 5, Number 30

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24 July 2000                                  Vol. 5, No. 30


       Zero Saga & Confusions with Numbers - Arsham
 DPGraph - Parker | Flying Between Two Trains - Dr. Math FAQ

         Prof. Hossein Arsham; University of Baltimore 

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. 


                    DPGRAPH - David Parker
               Dynamic Photorealistic Graphing


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 time-dependent (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 
    time-dependent 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.


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.


                   New from the Dr. Math FAQ

                   FLYING BETWEEN TWO TRAINS

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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