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Messages - GustavoHM

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HP Calculators / Re: Math problems?
« on: September 18, 2014, 11:46:34 am »
Hello Tim and DJ Omnimaga!
Thank you both for your replies.


Tim, I do understand that limited precision calculations have, well, limited precision and will be subjected to imprecision when dealing with recurring decimals and such. That explains the 0.999... answer in Home mode as you said. And now I see how students would interpret the result and learn with it.
However, how can CAS do infinite precision calculations in a limited precision calculator?

CAS gives 1 in both exact and aproximate answer modes, even when I "shift+Enter" the expression to calculate the aproximate answer first, so it doesn't seem to use the exact result as base for the aproximate one. 
How does it achieve 1 then?


I did look up the 1/0 answer in WolframAlpha after my post and did some research in complex infinities. It is a rather interesting subject, but complicated enough to support the "undefined" category when dealing with common math.


Thank you again for your comprehensive reply. Now I can appreciate my Prime even more after learning its philosophies. And, of course, brag a bit about it with my TI-owner friends ;)


GHM

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HP Calculators / Math problems?
« on: September 15, 2014, 11:49:47 pm »
Hello!
I'm a proud Prime owner and, as my first graphing calc, I could not be happier. :hyper:
However there are two problems(?) that I found while playing around with it:

On the Home screen, doing (1/9)*9 gives me 0.999... , when it should result in 1. Switching between exact and approximate modes converts 0.99... into 1. I know it might be related to floating point calculation and obvious approximations, but either way, doing that with CAS gives only 1. ???

And the second problem is dividing by zero in CAS, which results in infinity. The same calculation in Home results in Error, which is expected, as, for all I know, division by zero is supposed to be undefined.

Please enlighten me if I misinterpreted the results.

GHM

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