For question 5, I think TI should have the same reaction, as in wishing to allow third-party development in C while keepimg calculators safe for testing purposes, but instead they are like, BLOCK EVERYTHING.

That's because the Casio people are customer orientated and polite but while the TI people are a bunch of as oles so I wouldn't expect that to ever change.  They are what they are.  Evil is as evil does.  Btw,  People here don't like the way TI treats them but they still spend their money with TI.  Why is that?  In protest against the way ti treats me as a customer I didn't buy an nspire and I havn't bought one and I won't buy one.  I don't need their additude nor their nshit.

Quote from: Hot_Dog on February 23, 2012, 12:37:49 pm

Guys, please no "divide by zero" funny pictures on this topic.

Somebody gave me a good reason that 0/0 isn't valid.  But I can't remember what it was.

Let's represent 0/0 as something else, namely 0*(1/0). This makes it obvious what the main problem is. Division by 0, of *any* number, whether a real or a rational number, simply isn't defined in the standard system of reals. It's not immediately obvious why this is so. 0 doesn't appear to be a special number (besides being the null quantity) until we look at the definition of a field, which the set of real numbers forms when combined with the operations of addition, negation, multiplication, and multiplicative inversion (Finding A=B^-1). Basically, 0 is what is called the additive identity, which means that any number from the field can be added to it and you will get the same number back out. A+additive identity=A in any field F. The important part of being defined as the additive identity is that by definition, division by the additive identity is undefined in any non-trivial field. It's just a matter of definition. Things go funky when you allow it and inconsistencies creep in, such as being able to "prove" that 1=2 in the real numbers.


TL;DR 0/0 is undefined because convention says it's undefined to make things work out properly. You can say 0/0 is whatever you want, but as soon as you do so, everything else falls apart.

Also, now that I've written this, I see that adriweb beat me to it with a well timed

Quote

Excellent explanation.  Thank you.

Yeah, we're learning Calculus (mostly differential atm) in Year 12, and we had a long discussion about limits.
The limit technically does not exist at the given value e.g.: lim h->0 f(x)=3x^2+7x-5.
At h=0 the equation is undefined as we're dividing by 0 (The answer could be infinity, for all we know, or it could be 9000.00000032), but the point of Calculus (well at least this part of calculus) is that we are to find the theoretical derivative of the equation when h=0, even though it technically does not exist.

Hope that made some sense, and I may have made a mistake.

Huh?  For continuous functions, i.e., functions whose graphs don't have a break in them and can be drawn without lifting your pencil from the paper, the limit of f(x) as x approaches a is f(a), the value of the function at a.  Furthermore, all polynomials are continuous. So technically what you said is incorrect for polynomials but can be correct for other functions which have a discontinuity where the limit is being taken.  For example, the rational function (x^2-x)/(x-1) has a discontinuity at x=1 because the function is not defined and doesn't exist there because of division by zero (the denominator is zero), however the limit as x approaches one does exist and is one.  You can see from the graph, that as x approaches one from either direction it gets closer and closer to one but "at" one we know the function doesn't exist.  On the other hand, the polynomial function x^2-x exists at and is continuous at x=1 so the limit of f(x)=x^2-x as x approaches one is f(1) (the value of the function AT the value that x is approaching) which is zero.

If those calc's are not for sale, how does TI dump them on the market?  Don't you just love the way TI sets up unsuspecting customers for a bummer!

I'm worried they might not bother, especially in countries where touchscreen calcs are disallowed in most tests.

Good point.  I'd settle for a non-touch screen if it was color and used the class pad cas.  I would prefer the touch screen given the choice however.  I never cared for touch screens because the stylus gets lost all the time but with the iPad - no stylus required but one can be used and now sorry to say, I'm spoiled.

BTW, Apple sold 15 million iPads in the first quarter of last alone and probably over 200 million all told, so clearly touch screens are here to stay and the testing authorities are going to have to update their thinking or be replaced. The schools that are buying class sets of iPads and putting digital text books and calculator apps on them are going to demand it.  This change from books to digital books on iPads is coming with the momentum of a freight train and can't be stopped.

Quote from: flyingfisch on February 03, 2012, 02:01:20 pm

Quote from: apcalc on February 02, 2012, 06:47:42 pm

Quote from: Spyro543 on February 02, 2012, 05:16:07 pm

Even though it doesn't have a color screen, who cares? A calc with a touchscreen is always awesome

Yes!

Bingo! ka-Ching.  You are absolutely, totally correct and I agree with you completely .

I agree!  It is sad to see new things like this being downgraded just because it does not have a color screen.  Although the color screen is nice, it certainly does not define the product!

I agree and disagree at the same time. CP300's are in the $150 range. I think that if casio is going to continue to use a B&W screen, they should lower the price. Or they can keep the same price and give it a color screen.

You seem to forget that the Ti-84 series is a staple in most American schools. They have a black and white low res. display, and have remained relatively unchanged since they were introduced as the TI-82 in 1993. The Z80 is much more ancient than the class pad's processor and the screen is of even lower quality. And oh yea, they're expensive too. I guess despite being "outdated junk", they still server their intended purpose. Since the class pad is more advanced then the standard, I would hardly classify it as "junk". It seems a fancy high res. screen really isn't necessary.

Thank you for making my point.  The 84 series uses 20 year old technology as you said.  Only the TI cx series uses a modern screen and it is 5 or 6 years old.  It's not about a fancy screen not being necessary.  If the basis for making a judgement is what is necessary, then we should not be using calculators at all.  My point is that calculators use old technology which is ok if that cost savings is passed on to you but it is not.  So if you don't mind being ripped off go for it.  That is your decision to make and your money to spend.  As for myself, I already have some old calculators that have old technology so I there is no point in wasting money on another another.  Perhaps you spend your parents money in which case getting quality for the money is not an issue.