Variation table for HP39gII

08132012, 01:15 PM
Mic, Expliquez, s.v.p. En anglais préférablement. Merci.
08132012, 01:27 PM
Pour quoi?
08132012, 01:29 PM
I posted in english, no ?
08132012, 01:34 PM
'Tableau de variation' in french, is a table representative of the sign of the derivative of a function. It is used, usually for analyzing a function prior to its plotting 'by hand'. Regards.
08132012, 01:37 PM
Thanks for the explanation. It's an idea I hadn't heard of before.
08132012, 01:42 PM
Thank you for your explanation :) Nevertheless, on a calculator which allows for graphing the function or its derivative itself I hesitate to see much value in such a "variation table" just telling me there's something anywhere in between infinity and +infinity. I dare say I'd guessed that [;) but presumably I missed something essential.
08132012, 02:37 PM
The command TABVAR in the 48 series does just this. Doesn't actually plot, but has a nice numerical only table identifying all the important bits of the function and the behavior in the various. TW
08132012, 02:50 PM
Not in the entire series, however.
08132012, 02:58 PM
Well, it is a bit of historical interest now. But before graphing calculators were widely spread among students it was a very 'popular' exercise in math teaching for 'analyzing a function'. The game was to plot the function by hand. There is a kind of systematic method which was teach intensely to math students. And it is a very concrete and immediate application of the notion of derivative. Beside history, it is of interest for functions with discontinuities where graphing algorithms can fail and for getting a firm understanding of a function. Sometimes it is amazing what you can do with a paper and a pencil, even without an HP calculator....;)
08132012, 03:22 PM
Hmm. Thought was introduced on the S. Must have been the G then. TW
08132012, 03:43 PM
For example the 'variation table' of X^2+3*X+1
In just one glance, you see the essential On 50G, it's 'X^2+3*X+1' TABVAR
08132012, 04:19 PM
Table is useful to study the signs of the derivative and to draw with precision the graph.
08132012, 05:05 PM
I said it was a bit historical because french students, as the others...jump first on their calculator, then think about the strange plot they get and finally try to get a table of variation with the very same calculator if possible. ;) Turning the brain on before the calculator is a vanishing habit those days.... Regards
08132012, 07:42 PM
I think that you need to install Erable 3.2 on the 48G/GX to get TABVAR.
08142012, 12:14 AM
Well, I guess I was completely wrong on all counts. I was certain I used it on my first HP  a 48G. I know I didn't install anything fancy on it. That was in 1997 or so though, so I must be getting old as my memory is failing. :) TW 
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