Variation table for HP39gII  Printable Version + HP Forums (https://archived.hpcalc.org/museumforum) + Forum: HP Museum Forums (https://archived.hpcalc.org/museumforum/forum1.html) + Forum: Old HP Forum Archives (https://archived.hpcalc.org/museumforum/forum2.html) + Thread: Variation table for HP39gII (/thread229133.html) 
Variation table for HP39gII  Mic  08132012 For ax²+bx+c functions :
Download : Edited: 13 Aug 2012, 12:45 p.m.
Re: Variation table for HP39gII  Peter Murphy (Livermore)  08132012 Mic,
Expliquez, s.v.p. En anglais préférablement. Merci.
Re: Variation table for HP39gII  Walter B  08132012 Pour quoi?
Re: Variation table for HP39gII  Mic  08132012 I posted in english, no ? Re: Variation table for HP39gII  Bunuel66  08132012 '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.
Re: Variation table for HP39gII  Peter Murphy (Livermore)  08132012 Thanks for the explanation. It's an idea I hadn't heard of before.
Re: Variation table for HP39gII  Walter B  08132012 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.
Re: Variation table for HP39gII  Tim Wessman  08132012 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
Re: Variation table for HP39gII  Peter Murphy (Livermore)  08132012 Not in the entire series, however.
Re: Variation table for HP39gII  Bunuel66  08132012 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....;)
Re: Variation table for HP39gII  Tim Wessman  08132012 Hmm. Thought was introduced on the S. Must have been the G then.
TW
Re: Variation table for HP39gII  Gilles Carpentier  08132012 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
Re: Variation table for HP39gII  Mic  08132012 Table is useful to study the signs of the derivative and to draw with precision the graph. Re: Variation table for HP39gII  Bunuel66  08132012 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
Re: Variation table for HP39gII  Didier Lachieze  08132012 I think that you need to install Erable 3.2 on the 48G/GX to get TABVAR.
Re: Variation table for HP39gII  Tim Wessman  08142012 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
