View Single Post
  #3   Report Post  
Old May 8th 09, 06:43 PM posted to rec.radio.amateur.antenna
Antonio Vernucci Antonio Vernucci is offline
external usenet poster
 
First recorded activity by RadioBanter: Jun 2006
Posts: 395
Default Be careful when using Excel



--
------------------------------------------------------
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
------------------------------------------------------
"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.

73

Tony I0JX