|A more useful standard display format|
Message #1 Posted by Dieter on 1 Apr 2011, 9:24 a.m.
First time users of classic HP calculators may be slighty puzzled when the display shows 0,00 or 0,0000 as the device is turned on. I even remember the question why "such an expensive calculator" would only give a three-digit result, while a cheap 5-Euro-Casio... ;-)
Both the first HP (-35) and newer models (last 20 years) offer a display format ALL or STD where the whole singificant mantissa is shown. So 1/8 is displayed as 0,125 and 1/3 as 3,33333333333E-1. The WP34s project even uses this format as its default display mode.
However, for everyday use there's a major drawback in this implementation. Even moderately small values like 0,5153... or 0,03543... are displayed in scientific notation, which means that the user's eye has to move all the way across the display to its right end, read the exponent there and translate it back into a meaningful result. As far as I am concerned, I do not want to see "2,04135445874E-2" if a calculated price simply is "2 cents", or "3,35283587165E-1" if the result is 33,5% or even just "roughly one third". It's even worse on the HP-35s with its 14-digit-display hiding the complete exponent. The user has to scroll the display manually before he is able to see whether the result is 0,33 or 0,03 or something even less.
A simple FIX 2 or FIX 4 is not an option here since in this case the major advantages of the ALL format are lost: if the result is an integer, the display shows an integer (3 instead of 3,00 which could also stand for 2,99835 or 3,00208). Generally, useless trailing zeroes are omitted while on the other hand all significant digits are visible.
Okay, what's my point now? I would like to suggest a useful standard display format similar to what I remember from earlier non-HP calculators: Moderately small results should not be displayed in scientific notation, even if this means the last two mantissa digits are not visible. The advantage is a much more intuitive and "natural" display format that allows the user to capture the result faster, easier and without any "exponent translation error". My suggestion is: All numbers with absolute value >= 0,01 or 0,001 should be displayed like 0,012345... resp. 0,0012345... and only values below this limit should be displayed in scientific notation. Like this:
current display improved display
For obvious reasons this cannot be implemented in current HP calculators. But it can be done on the WP34s. :-)