"Antonio Vernucci" wrote in
:

Subject: Be careful when using Excel
From: "Antonio Vernucci"
Newsgroups: rec.radio.amateur.antenna
Reply-To: "Antonio Vernucci"



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Antonio Vernucci, I0JX US call: K0JX
Beacons: 50.004 MHz & 70.088 MHz
Home page: http://www.qsl.net/i0jx
e-mail: k0jx {at} amsat {dot} org
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"Jeff" ha scritto nel messaggio
. com...
"Antonio Vernucci" wrote in message
.. .
I think this message can be of interest for those using Excel for
antenna calculations.

Write in one cell: =(-A1^2 + 8) Note: the exponent of A1 is 2
(and not 2+8=10) because Excel performs squaring before summing

Write in another cell: =(8 - A1^2)

They look pretty much the same

But give A1 any non-zero value and see what happen.

73

Tony I0JX
Rome, Italy


I see it give the correct answers!!!

eg when A1 =2 the first formula =12 and the second =4

-2 squared =4
So 4 plus 8 = 12

2 squared =4
So 8 - 4 = 4

8 - (2 squared) = 4

Yes, but the way Excel works is deceiving.

As a matter of fact, with reference to the general mathematical
principle A+B = B+A, let us have:
A= -A1^2
B = 8

Then, one would expect that -A1^2 + 8 is the same as 8 - A1^2, which
is not the way Excel works.

So just what were you expecting to get? Were you expecting -A1^2 to
really be -(A1^2)?

-Bruce