At 01:25 PM 9/16/99 , Stan Sieler wrote:
>Wirt writes:
> >          C = 5/9 * (F-32)
> >          F = 9/5 * C + 32
>
>There's the difference between Wirt and me:
>
>    Wirt remembers the formulae (and can spell formulae)
>
>    I have to reverse engineer the formula when I need it ...
>    luckily, I remember 0 C = 32 F, and 100 C = 212 F.


The data points and the formulae for the line mapping Celsius and
Fahrenheit are simply two ways of perceiving the same thing.  Since the
Celsius scale changes 100 units over the same range as Fahrenheit changes
180 units, the ratio of their slope is 100/180 which reduces to 5/9 and the
"0 C = 32 F" makes it obvious that the Y-intercept of the conversion
function is at 32 F.  It's as simple as thinking of electromagnetic
radiation as a dual nature, both waves and particles at the same time, only
the observation method makes it appear to be different.  :)

At 09:05:38 -0700 Thu, 16 Sep 1999 , Art Bahrs wrote:
>        Fahrenheit temp approximately equals  (2 * Celsius Temp) + 30 degrees
>
>This works well for me :)   Tho it gets off when you test it against the one
>poinnt at which the Celsius and Fahrenheit scales are equal :)  Anyone
>remember
>that one ?

The hack "F = 2 * C + 30" is an approximation that gives a "good enough"
number for most folks at typical ambient air temperatures, but note that
it's only precise at the point 10 C = 50 F and as the temperature varies
(up or down) from that point the error grows steadily.  At 77 F = 25 C the
"hack" is off by 3 F.

And, -40 C = -40 F
--
Jeff Woods
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