Be careful when using Excel
 

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

Be careful when using Excel
 

"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


Jeff

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

Be careful when using Excel
 

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.

Be careful when using Excel
 

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.

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

Be careful when using Excel
 

Antonio Vernucci wrote:
But give A1 any non-zero value and see what happen.

It appears that EXCEL uses the Microsoft BASIC engine
for its calculations. Those problems are well understood
by BASIC users. Hint: use more parentheses.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Be careful when using Excel
 

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

Be careful when using Excel
 

It appears that EXCEL uses the Microsoft BASIC engine
for its calculations. Those problems are well understood
by BASIC users. Hint: use more parentheses.

Yes, that is what I normally do.

Anyway it is good to keep in mind that:

- for Excel: (-2^2 + 8) = 12

- for Visual Basic: (-2^2 + 8) = 4

73

Tony I0JX

Be careful when using Excel
 

Cecil Moore wrote:
Antonio Vernucci wrote:
But give A1 any non-zero value and see what happen.

It appears that EXCEL uses the Microsoft BASIC engine
for its calculations. Those problems are well understood
by BASIC users. Hint: use more parentheses.


More Cowbell maybe?