[net.math] more about e

ctb@ihlpf.UUCP (baumer, c.t.) (07/08/84)

#N:ihlpf:6200023:000:1033
ihlpf!ctb    Jul  7 12:45:00 1984

.

ah, you beat me to it, barryw.   i also dug out asimov on numbers.
i hadn't read it in years. i just wanted to throw in an extra
comment that the book deals with all kinds of interesting 'number'
stuff - pi, factorials, fibonacci series, googleplex, calendars etc. etc.

your average person would look at the above examples and say 'i know
all that junk'.  true, but there's a LOT more.  it goes into the history 
behind various numbers, calendars, etc. almost treating them like subjects 
of a biography.  it's more than just the math, it's all the interesting 
stuff and personalities surrounding the math, too! asimov is GREAT at 
mixing entertainment AND learning.

for example, when i was first reading asimov on numbers, (in high school)
i didn't know  

	e**(pi * i) = -1   

little tidbits like that are fun to run across.  what an interesting 
relationship between three pretty big heavyweights (as far as numbers go :-),
e, pi, and i!


	ron	(replies to:  ihnp4!ihdev!rjv)

ps:  anyone want to prove the above equality?

ljdickey@watmath.UUCP (Lee Dickey) (07/09/84)

I think that identity is really neat too...  I like to
write it in another way...

        0 = 1 + e ** ( i * pi )

Then in addition to the three heavies you mentioned, there are 
two more, namely 0 and 1.
But also, notice that there are 4 other heavies in there too...
addition, multiplication, exponentiation, and equality.
This identity falls out of Euler's Formula, which comes from 
the definitions of the power series for exp(x), sin(x), and cos(x).  
If you can remember the first series, you can recall the other two
by plugging in    i*t   and sorting out the  i  parts.  Of course
I have to look carefully at what convergence of complex power
series means before I find the "proof" convincing, but the formal
manipulation is easy and entertaining.
-- 
  Lee Dickey, University of Waterloo.  (ljdickey@watmath.UUCP)
 	... {allegra, decvax} !watmath!ljdickey