Re: Graphing Calc Plotting Speed Benchmarks Message #3 Posted by Chuck on 9 Feb 2007, 12:54 a.m., in response to message #1 by Warren Anderson
Possible improvement in the 50g. So far I've been impressed in the speed over my old 48SX. However.....
I ran into an odd problem with having the 50g find the extremum of a function today. We were solving the classic problem of optimizing the viewing angle in a theatre where the seats are on a slant. To make the equation more manageable I used two variables for subequations, and then graphed the main equation...
as = (x Sin(25) - 6)^2 + (x Cos(25) + 7)^2
bs = (28 - x Sin(25))^2 + (x Cos(25) + 7)^2
eq = ArcCos((as + bs - 484) / sqrt(4 as bs))
Note: the angle is 25 degrees.
Graphing eq produced the correct graph, but the extr command gave values wherever the initial placement of the cursor was; not anywhere near the maximum.
However, evaluating eq and regraphing the "expanded" function, the extr command gave the correct optimum x = 9.295.
I hate to say it, but my students TI84's did this just fine using Y1, Y2 and Y3, and found the maximum in about 1/5th the time. :(
CHUCK
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