Graphing Calc Plotting Speed Benchmarks

[Warren Anderson]

Because I'm lazy and can ask experts instead of trying myself...

I recently obtained a 48G+ because it seemed to be the ultimate product of old HP, subject of Wicke's books, RPN/RPL, build quality, etc.

I was astonished at how long it took to plot the "Woodyard/Kahan integral" over the default interval. Seemed like more than a minute. Then an equally long wait after I changed the interval. Granted, I spent only a few minutes with it, but found the calculator unusable for interactive function analysis based on the output delay. I did a full clear first. Were there some flags I didn't set but should have that would have sped it up?

I have several excellent graphing/CAS programs on a big-screen Mac, but thought it would be cool to mess around on the small screen too using vintage tools.

The 48G+ is no longer with me, but a 50g is not out of reach, and I'm lucky to own an Xpander which I never use because the battery insertion is a major pain and screen contrast atrocious.

Are there any plotting/graphing/function analysis benchmarks comparing 48G to 50G to Xpander? Imagine the performance has improved markedly with new processors.

[Dia C. Tran]

If you are into plotting then either the new calculator or better yet a software package running on your PC. The 48's are great calculator but the screen resolution is too low for good plotting.

[Chuck]

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