On Fri, 08 May 2009 20:59:35 +0200, Helmut Wabnig hwabnig@ .- --- -.
dotat wrote:

On Fri, 8 May 2009 18:36:08 +0200, "Antonio Vernucci"
wrote:

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

In correct mathematical convention the expression
let A1 = 2 then

-A1^2 must yield

-A1^2 = -4

otherwise we would have to write
(-A1)^2 = 4

EXCEL does it the wrong way in example 1: =(-A1^2 + 8) = 12
and does it correctly in example 2 =(8 - A1^2) = 4.
But they are from Microsoft and they can do whatever they want.

w.
TYPO correction
and does it correctly in example 2: =(8 - A1^2) = 4.

--
------------------------------------------------------
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
------------------------------------------------------
"Helmut Wabnig" hwabnig@ .- --- -. dotat ha scritto nel messaggio
...
On Fri, 08 May 2009 20:59:35 +0200, Helmut Wabnig hwabnig@ .- --- -.
dotat wrote:

On Fri, 8 May 2009 18:36:08 +0200, "Antonio Vernucci"
wrote:

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

In correct mathematical convention the expression
let A1 = 2 then

-A1^2 must yield

-A1^2 = -4

otherwise we would have to write
(-A1)^2 = 4

EXCEL does it the wrong way in example 1: =(-A1^2 + 8) = 12
and does it correctly in example 2 =(8 - A1^2) = 4.
But they are from Microsoft and they can do whatever they want.

w.
TYPO correction
and does it correctly in example 2: =(8 - A1^2) = 4.

In correct mathematical convention the expression
let A1 = 2 then

-A1^2 must yield

-A1^2 = -4

otherwise we would have to write
(-A1)^2 = 4

I share your opinion. But there are two Microsofts.

- for Microsoft#1, that is Excel: (-2^2 + 8) = 12

- for Microsoft#2, that is Visual Basic: (-2^2 + 8) = 4

Funny, isn't it?

Antonio I0JX

"Antonio Vernucci" wrote in message
. ..
In correct mathematical convention the expression
let A1 = 2 then

-A1^2 must yield
-A1^2 = -4

otherwise we would have to write
(-A1)^2 = 4

I share your opinion. But there are two Microsofts.

- for Microsoft#1, that is Excel: (-2^2 + 8) = 12

- for Microsoft#2, that is Visual Basic: (-2^2 + 8) = 4


at least they are doing what their help says they should do. in vb6
exponentiation is done before negation. in excel negation is done before
exponentiation. when in doubt use more parenthesis than you think you
should to be sure the calculation is done in the order you are expecting.