|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
The other points, however, forget them. Who needs (the following)?
- y-th root of x
- Population standard deviations
- Roll down on the keyboard
- Selected SI-British conversions
First off, I made several careless errors. I should have stated
- "x-th root of y"
- Roll up on the keyboard
And, you should have stated, "SD of the sample".
Shifted y-th root is absolutely superfluous.
"x-th root of y" is a convenience that allows odd-integer roots of negative numbers to be found adroitly. This is useful in programs, should this situation arise. Also, the result using "x-th 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 "x-th root of y" may explain why the unshifted 1/x and y^x are adjacent on the Voyager-series keyboards.
For example, try taking the cube root of (e^pi)8, using each of the two methods. I get a difference of 4E-8, or 4 ULP of a 12-digit result. Or, the cube root of 989,999,999,999: I get a difference of 9E-8, or 9 ULP of a 12-digit result.
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 HP-32S, HP-10C, and original HP-35 did without it. On the HP-42S, 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 non-proportional.
It's a 32s with maximum clutter.
On clutter: The HP-32SII arrangement is quite logical -- about as good as it could be done -- although not perfect as on the HP-15C. The HP-32SII looks somewhat cluttered because the yellow and blue shifted functions are adjacent instead of aligned vertically, and the letters for variables are also imprinted.
Edited: 12 Oct 2008, 8:08 p.m. after one or more responses were posted