Re: 42S vs 32SII functions Message #13 Posted by Karl Schneider on 12 Oct 2008, 1:34 p.m., in response to message #9 by Walter B
Walter 
Quote:
The other points, however, forget them. Who needs (the following)?
 yth root of x
 Population standard deviations
 Roll down on the keyboard
 Selected SIBritish conversions
First off, I made several careless errors. I should have stated
 "xth root of y"
 Roll up on the keyboard
And, you should have stated, "SD of the sample".
Quote:
Shifted yth root is absolutely superfluous.
"xth root of y" is a convenience that allows oddinteger roots of negative numbers to be found adroitly. This is useful in programs, should this situation arise. Also, the result using "xth root of y" may be more accurate by one or more ULP than taking 1/x followed by y^x, as the internal result of 1/x is not rounded to 12 digits for output before taking y^x. Absence of "xth root of y" may explain why the unshifted 1/x and y^x are adjacent on the Voyagerseries keyboards.
For example, try taking the cube root of (e^pi)^{8}, using each of the two methods. I get a difference of 4E8, or 4 ULP of a 12digit result. Or, the cube root of 989,999,999,999: I get a difference of 9E8, or 9 ULP of a 12digit result.
Quote:
Population SD is less useful than SD of the mean. Etc. ;)
As for SD, we must consider what the user's task is. Population SD would be calculated for the quiz scores of a classroom of pupils, as 25 or so would represent the entire population. Sample SD would be used for a few trials of an experiment. However, most users nowadays would probably do these calculations using a spreadsheet, anyway...
"Roll up" is a very handy convenience, especially in programs. It's not absolutely essential; the HP32S, HP10C, and original HP35 did without it. On the HP42S, it's available only from the function catalog.
As for SI<>British conversions, that's been discussed (and argued) previously in the Forum. The conversions are useful for "us in the US", particularly the temperature conversions, which are nonproportional.
Quote:
It's a 32s with maximum clutter.
On clutter: The HP32SII arrangement is quite logical  about as good as it could be done  although not perfect as on the HP15C. The HP32SII looks somewhat cluttered because the yellow and blue shifted functions are adjacent instead of aligned vertically, and the letters for variables are also imprinted.
 KS
Edited: 12 Oct 2008, 8:08 p.m. after one or more responses were posted
