## Saturday, March 23, 2013

### Spring has Sprung: Pocket Ref, TI-30XA, Old HP Manuals, Review and more HP 39gii is coming

Hi everyone! Greetings from the Starbucks in Azusa, CA. Today's blog entry is a hodgepodge. Part 5 of the HP 39gii Programming tutorial - I am planning to have that ready by next week; totally apologize for the long delay.

I am very thankful my family is doing fine and my dad and uncle are both home from the hospital.

Pocket Ref: A Book of Everything?

While at Harbor Freight I found this book: "Pocket Ref 4th Edition" compiled by Thomas J. Glover; picked it up for \$10. This reference edition has practically everything technical: physics, computer, mechanics, construction, automotive equations, electrical engineering equations, table of elements and chemical molecules, weights, densities, and perpetual calendars; just to name a few topics. This book has become a permanent part of things I take everywhere. Hopefully this reference will be used for future blog entries.

The TI-30XA: Then and Now

I finally broke down and got a new version of the TI-30XA by Texas Instruments. I have been resisting it for so long since I preferred the solar version over the battery version. What got me to finally purchase it is the article I saw on www.datamath.org, which details the logarithm bug.

Basically, the calculation goes haywire for:

(1) ln(1+x) when x is really small, and

(2) (1+1/n)^n for really large n.

I tested both calculations for the calculators. I also used the built in calculator in the google.com search engine. If you type in a mathematical calculation in google, it will get you the answer! Google also handles conversions and graphing functions.

Both the TI-30XAs (solar and battery) returned the same answers, so nothing has changed in the algorithm.

(1) ln(1 + x)

x=10^-2
TI-30XA: 0.009950331

x=10^-8
TI-30XA: 0.000000001

(2) (1+1/n)^n

n = 10^2
TI-30XA: 2.70481383

n = 10^8
TI-30XA: 2.7183727

Out of curiosity, the TI-84+ agrees with Google. So this is a cautionary tale with the TI-30XA: be careful with arguments involving 1+x, where x is real small (like powers of 10^-6 or smaller) in any calculations involving logarithms and powers.

On the plus side, the battery TI-30XA retains memory when the ON button is pressed and the numbers are larger and in bold.

Review of the TI-84+ Color Silver Edition Coming Soon

Speaking of Texas Instruments calculators, my TI-84+ C Silver Edition is going to arrive at my doorstep in the coming week. That was my birthday present to myself. By clicking in this sentence, you can read how I initially felt about the TI-84+ CSE. I did read good reviews about it (This sentence is a link to one review, done by Christopher Mitchell (Cemetech). )and will give an impression when I actually have a TI-84+ CSE in my hands.

Old Hewlett Packard Manuals: They have a calculation manual for everything!

Back in the 1970s and 1980s, when pocket calculators were in their beginning stages, Hewlett Packard released detailed calculator manuals for not only their products (HP 35, HP 45, HP 67, etc), they had manuals covering almost every topic conceivable. To name a few: engineering, finance, games, biology, and one even covered astrology. Every now and then I like to study some of these manuals and try to see if I can do it (mostly with today's calculators). It is a really fun way to pass the time.

Several years ago, I ordered the DVD that contains a collection of manuals from The Museum of HP Calculators. You can order the DVD by clicking on this link.. The link will contain another link of the manuals the DVDs contain. I hope to refer to these manuals in future blog entries.

So, more HP 39gii Programming Tutorial, a review of the TI-84+ CSE, and more is coming. Thank you as always and take care,

Eddie

This blog is property of Edward Shore. 2013

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