|Re: HMS Calculations 28S vs 42S - bug?|
Message #3 Posted by Chris Randle (Lincoln, UK) on 9 Oct 2001, 3:40 p.m.,
in response to message #2 by Vieira, Luiz C. (Brazil)
OK. I've come to the conclusion that it's not a bug. In fact, I think it's a particularly elegant feature(!) although I can't find any reference to it in the manuals.
Obviously, adding HMS numbers without using the HMS+ function is a bit daft, but the problem will also surface if you do: 0.2 [HMS->] [->HMS] which yields 0.196. Again, the 42S has no "problem" with this. Here's my take on it:
You know how SIN(pi), when pi is expressed as a number, isn't zero? That's because the numeric pi isn't (and never can be) exactly pi. I think HP went looking for more places to be pedantic. 20 minutes expressed as degrees is 0.333... recurring. So when you convert 0.333... (to the limit of the calculator's accuracy) back to minutes, it says "well, it's not exactly 20 minutes, more like 19 minutes 60 seconds". It's quite clever really. It's the same thing, but it warns you that it's not necessarily quite right.
I was thinking this could be extended to 1 [ENTER] 3 / 3 * resulting in 0.X where X would be a new symbol for ten as in the Roman X. "Nought point ten" is 1, but not quite!