The ticalc.org Newsletter
http://www.ticalc.org/
November 1998 - Volume 1, Issue 1
IN THIS ISSUE
Letter from the Editor
Calculator News
Graphing Piecewise Functions
Interview with Brett Barwick
Subscribing and Unsubscribing Information
Web Archive
LETTER FROM THE EDITOR
Thank you for reading the ticalc.org newsletter! This newsletter has recently undergone some changes. I, Kirk Meyer, have become the editor, and it has been changed from a weekly newsletter to a monthly newsletter. Because of this change, the program of the week award has been eliminated, and the program of the month awards will begin in January. If you have anything that you would like to have published in this newsletter, please send it to newsletter@ticalc.org. Each month I will print one letter that I choosein a "Letter to the Editor" section. You can send letters regarding just about anything as long as they are constructive. Send your letters to the editor to newsletter@ticalc.org.
Kirk Meyer
CALCULATOR NEWS
In ticalc.org news, two new staff members have been added: Kirk Meyer, and Ahmed El-He
lw. I am in charge of maintaining the recently overhauled Reviews section and also of editing this newsletter. Ahmed is in charge of maintaining the new Program Ideas and Upcoming Programs sections. Additionally, The TI-Files, a major competitor of ticalc.org, acquired their own domain name. They are only the second TI calculator site to do so. In other news, two programming alliances have been formed. The ACZ (Assembly Coders Zenith) and Z80 Assembly Coders. The ACZ consists of CLEM, Dux Gregis, JBrett, David Phillips, and Dave Scheltema. The Z80 Assembly Coders consists of Will Dempster, InFuZeD, Ian Kaplan, and Jesse Keane. I retired from programming calculators and released all of my source code to the public. New programs of note include SOS v1.6, Doors OS v0.8 Beta (for the TI-89 and the TI-92 Plus), and Crash v1.5. Texas Instruments has released the original TI-89 Flash ROM to the public as well as Flash ROM upgrades to the TI-73 and the TI-92 Plus.
GRAPHING PIECEWISE FUNCTIONS
This month I have decided to write an article about how to graph piecewise functions on nearly any TI graphing calculator (although I haven't tried it on all of them). One caveat before you start: you will not be able to calculate derivatives of piecewise functions or draw tangent lines. Most other functions should work including integration. First I will start by saying how this works. When the TI tests a condition, it returns 1 if it is true and 0 if it is false. So if you multiply a condition by an expression that expression will appear only if the condition is true. With that in mind, here is how to graph piecewise functions. Suppose you have y=x for x less than zero and y=x+1 for x greater than or equal to zero. You would enter this as y1=(x<0)(x)+(x>=0)(x+1). Simply multiply each condition by its corresponding function and add them all together. You can have as many pieces as you want with this method and it will still be treated as one function (except for derivatives). Notice that this will work for all kinds of graphs, not just functions. It will work for polar (with a condition on theta), parametric (with a condition on t), etc. I hope this is useful for you in some math class along the way!
INTERVIEW WITH BRETT BARWICK
Email: tbarwick@esn.net
ICQ UIN: 20607010
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Interview Log
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Kirk
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How old are you and what level of education do you have?
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JBrett
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I'm 13 and in the 8th grade.
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Kirk
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What do you plan to do after high school?
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JBrett
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I plan to major in computer engineering...
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Kirk
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Where do you think you want to work?
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JBrett
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I have never really thought about it... I think I would like to work for TI designing ROM's... I think that would be cool.
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Kirk
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What calculators do you own?
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JBrett
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A TI-86, but I have access to all of the Z-80 calculators at my school.
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Kirk
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Do you plan to buy any other calculators soon?
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JBrett
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Not soon, but possibly an 89 later.
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Kirk
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What do you use your calculator for most?
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JBrett
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Programming =)
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Kirk
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When and how did you find out about the "TI Community"?
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JBrett
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I found out about it when I was in 6th grade. I got my 86 and I wanted some games and stuff for it... I first found the TI-Files, but then I found ticalc.org and I have been going there ever since...
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Kirk
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When did you first visit ticalc.org?
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JBrett
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Sometime in the middle of 1997.
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Kirk
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What was the first program you ever wrote?
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JBrett
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Hehe... a small BASIC program called "bomb". It was a menu game where you had to go around and find the bomb and defuse it... I could make it much better now...
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Kirk
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How did you learn to program in assembly language?
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JBrett
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Through tutorials... mostly Trent Lillehaugen's. I wish I could have had Dux's back then...
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Kirk
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Do you have an idol TI programmer?
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JBrett
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SCaBBy, of course =) You too, but you stopped programming =P
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Kirk
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What projects are you working on now?
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JBrett
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Well, a game called Combat and another called Jenga... I am also working on some secret projects right now...
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Kirk
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You just recently joined an alliance, didn't you?
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JBrett
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Yes, it is the ACZ... we have many exciting things in store for the 86 and 89 communities... we are already working on tutorials and such for each calculator... we are merging 86 Central with our web page, which will hopefully open shortly.
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Kirk
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What advice would you give to people wanting to learn to program in assembly?
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JBrett
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Start small... learn the basics first and work up... Looking at source code helps and so do tutorials.
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SUBSCRIBING AND UNSUBSCRIBING INFORMATION
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WEB ARCHIVE
You can find all issues of the ticalc.org Newsletter in our Features section under Newsletter. The exact URL is http://www.ticalc.org/features/newsletter/index.html.
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