Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!haven!umbc3!math13.math.umbc.edu!rouben
From: rouben@math13.math.umbc.edu (Rouben Rostamian)
Newsgroups: comp.sys.handhelds
Subject: Re: temperature conversion (NOT A BUG!)
Message-ID: <4882@umbc3.UMBC.EDU>
Date: 24 Jan 91 06:47:20 GMT
References: <2D042619A000047E@gacvx1.gac.edu> <1991Jan24.014724.15552@nmt.edu>
Sender: newspost@umbc3.UMBC.EDU
Reply-To: rouben@math13.math.umbc.edu.UUCP (Rouben Rostamian)
Organization: Mathematics Department University of Maryland, Baltimore County
Lines: 45

In article <1991Jan24.014724.15552@nmt.edu> khbsnsr@nmt.edu (Kenneth Brunell) writes:
>In article <2D042619A000047E@gacvx1.gac.edu> U5513172@NMSUVM1.BITNET (Thomas L. Baca) writes:
>>Hello fellow HP-users,   I have what may be a silly question, but I
>>shall ask anyway.  WhenI add 25_'C ( read degree Celcius)  and 1_'F
>>on my HP 48SX, I get an answer of 537.67_'F.  What terribly simple thing
>>am I overlooking?
>Yes, it does return the answer in degrees rankine.  I just tried it.
>If you add degrees celsius to degrees farenheit, it returns the answer
>in degrees kelvin.  In either case, it does not change the units
>accordingly.  It must be a bug.  Apparently it neglects to convert back
>to the units it is supposed to output in.

It is not a bug.  Just gotta be careful when adding temperatures.

Digression:  How to boil water cheaply:
    Two bring a galon of water to boil, heat half of it to 106F,
    then another half to 106F, mix and stir well.
    Since 106F + 106F = 212F, then the mixture will be at the
    boiling temperature!

Anoter digression:
    32F + 32F = 64F, you say?  Convert this equation to centigrades.
    Recall 32F = 0C, and 64F = 17.8C, therefore:
    0C + 0C = 17.8C.   Uh... what did you expect 0C + 0C to be?

An experiment on the HP48:
    Try 0C + 0C on the HP48.  You will get 273.17C.  How does it arrive
    at this answer?  It converts the data to Kelvin first (0C = 273.15K)
    then:
	0C + 0C = 273.15K + 273.15K = 546.3K = 273.15C

See page 201 of the owner's manual.

The example from the previous posts:
    Again the data is converted to absolute scale first (Rankine, in
    this case) then added:
    25C + 1F = 536.67R + 469.67R = 997.34R = 537.67F

Get it?

--
Rouben Rostamian                          Telephone: (301) 455-2458
Department of Mathematics and Statistics  e-mail:
University of Maryland Baltimore County   bitnet: rostamian@umbc.bitnet
Baltimore, MD 21228,  U.S.A.              internet: rouben@math9.math.umbc.edu