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H->HMS conversion HP-15C vs. HP42S vs HP67
09-10-2018, 06:18 PM
Post: #47
RE: H->HMS conversion HP-15C vs. HP42S vs HP67
(09-10-2018 03:32 PM)Joe Horn Wrote:  
(09-10-2018 12:46 PM)Albert Chan Wrote:  Since 9°59'60" = 10°, "60 seconds bug" is not serious (easily fixed in the head)
At worse, this is a display bug, wrongly assumed number is decimal (see post 37).

(1) "Not serious"? Would anybody tolerate a digital clock that said the time is 1:29:60? No. It would be considered a buggy clock. Nor should we tolerate an HMS algorithm that returns 60 seconds or 60 minutes.

(2) "Only a display bug" is not true. Pekis' formulas (both his original and his "improved" one) return EXACTLY 1.29600000000 on the HP 50g for an input of 1.49999999999. That's not an artifact of display-mode rounding. It's a bug in the algorithm.

Calculator really need to know the fractions is minutes and seconds for correct round-up.
In this regard, my Casio get it right, dedicated DMS key for degree/minute/second.
So it knows 60 seconds to a minute, 60 minutes to a degree.
Best of all, user know it too, since it is displayed differently, as in 1°2°3°

Unfortunately, HP pick DD.MMSS decimal representation (a normal number !)
Even the calculator itself got confused. You can press DEG->DMS repeatedly, getting garbage.
It does not know ... (see post 37)

As long as calculator treat the "number" as decimal, it cannot be fix by patching formula.
Raw result of exactly 1.296, or will rounded as 1.296 doesn't matter.
Either way, the result need some cleaning up.

When I say, "not serious", "only a display bug", I meant cleaned-up result comes out the same.

Yes, I agreed this is not good. Did HP Prime still use this DD.MMSS form ?
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RE: H->HMS conversion HP-15C vs. HP42S vs HP67 - Albert Chan - 09-10-2018 06:18 PM

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