35 vs. 38 THROWDOWN!

[mdunn]

1. Woo – I rediscovered a pristine (sans battery & cover) HP 38E financial in my collection. Not much use to me, but still...

2. Unbelievably, the "3rd gen" 38 is significantly slower than the "gen 1" 35 for logs & exponentiation! Surprising...

3. Man, NiMH AAs are tight in that 38. The case already(?) has a hairline crack in't.

[mdunn]

HP38: Fixed decimal? Really?? :-}

[mdunn]

OK, I figured out how to set other FIXED decimal points. Ugh...what does HP have against floating decimal? It's ridiculous. Even the 35s can't do it IIRC... Do they not trust users to understand sigfigs?

(04-28-2018 11:06 PM)mdunn Wrote:  HP38: Fixed decimal? Really?? :-}

[Dieter]

(04-28-2018 11:16 PM)mdunn Wrote:  OK, I figured out how to set other FIXED decimal points. Ugh...what does HP have against floating decimal?

The original HP35 from 1972 only had a single display format, which I think is what you call "floating decimal". All (?) later models featured the FIX mode (fixed number of decimals, default 2 or later 4). This was complemented by the SCI format (scientific notation with tens exponent) and finally the ENG format (same as SCI, but the exponent is a multiple of 3). A "floating decimal" format was not supported.

This did not change until the late Eighties when HP began to add the "ALL" format (e.g. in the 42s). This displays as many decimals as required to show the complete number. So 1/4 is shown as "0,25" and 1/16 as "0,0625" while 3 is simply "3". On the other hand 1/7 becomes "1,42857142857 E–1". The alternative "0,14285714286" is not used as a 12-digit display would not allow displaying the ...57 and instead round to 6, so you only see 11 decimals. Since the mode is named "ALL" and not "MOST" this is not an option. ;-)

IMHO the best way to handle this is a configurable ALL mode. The only calculators I know of that offer such a mode are the WP34s and WP31s. Here you can set the threshold for the switch to scientific notation. My standard setting is ALL 3 which means that 1/700 is shown as 0,00142857143 while 1/7000 becomes 1,42857142857 E–4. ALL 0 would match HP's simple ALL mode.

(04-28-2018 11:16 PM)mdunn Wrote:  Even the 35s can't do it IIRC...

It can. The 35s offers an ALL mode.

Re. your other remarks in the first post:

(04-28-2018 11:01 PM)mdunn Wrote:  2. Unbelievably, the "3rd gen" 38 is significantly slower than the "gen 1" 35 for logs & exponentiation! Surprising...

May well be. But the results are more accurate.

(04-28-2018 11:01 PM)mdunn Wrote:  3. Man, NiMH AAs are tight in that 38. The case already(?) has a hairline crack in't.

The 38E/C is supposed to use its own dedicated battery pack. It is not designed to accept two single AA batteries. Doing so indeed can damage the battery compartment and/or the case. If you want to use two separate batteries you may choose flat-top cells. These are usually slightly shorter than regular button top cells with their protruding contacts.

Dieter