"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
------------------------------------------------------
"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

On Sat, 09 May 2009 16:48:19 +0000, Jim Higgins
wrote:

The proper precedence of mathematical operations is "PEMDAS," meaning
Parenthesis, Exponentiation, Mult/Div, Add/Sub.

Yep. The MS precidence is:
http://support.microsoft.com/kb/25189/EN-US/

: Range
space Intersection
, Union
- Negation
% Percentage
^ Exponentiation
* or / Multiplication or Division
+ or - Addition or Subtraction
& Text Operator
= = = Comparison Operators

Note that the negation (negative sign) operator comes before any
arithmetic operators. The problem comes from Excel inventing some
kind of distinction between negation (negative number) and
substraction. For arithmetic, there is none. For C programmers,
there is a difference (in the way the data is stored). More on the
subject:
http://mathforum.org/library/drmath/view/69058.html

That minus in front of the A1 is a unary negation, which is a
multiplication by minus 1, so it should be performed AFTER the
exponentiation, i.e; -A1^2 = -(A1^2)

Excel performs it before the exponentiation, i.e.; -A1^2 = (-A1)^2

The Excel answer is incorrect.

Yep. However, MS is not about to create problems by fixing the
problem. It would be a bad thing to have existing spreadsheets,
suddently give different results when run on updated and fixed
versions of Excel. Compatibility with old bugs is one reason that
bugs tend to be perpetuated. Old bugs and sleeping dogs should be
left alone.

73 de Jim, KB3PU

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
On Sat, 09 May 2009 16:48:19 +0000, Jim Higgins
wrote:

Yep. However, MS is not about to create problems by fixing the
problem. It would be a bad thing to have existing spreadsheets,
suddently give different results when run on updated and fixed
versions of Excel. Compatibility with old bugs is one reason that
bugs tend to be perpetuated. Old bugs and sleeping dogs should be
left alone.

73 de Jim, KB3PU


I sure am glad they finally fixed the simple calculator that Windows came
with. It had a major bug in it that if I remember correctly if you
substracted 3.1 from 3.11 you got zero. There were other numbers like that
also.

I think Intel had to recall a bunch of chips because of an error in the math
coprocessor part at one time.

Microsoft products are so full of 'problems' that if they ever put out an
error free product it would seem to be a mistake.

On Sat, 9 May 2009 14:15:19 -0500, "Ralph Mowery"
wrote:

I think Intel had to recall a bunch of chips because of an error in the math
coprocessor part at one time.

Close. See:
http://en.wikipedia.org/wiki/Pentium_FDIV_bug
for the details. Never mind that the fixed chips arrived after the
release of the next generation of Pentium processors, making
replacements for the older and slower chips a waste of effort. I had
several servers running the buggy Pentium 60 and 66Mhz chips.
Incidentally, they ran unusually hot and required extra cooling. I
applied to Intel for 3 replacement chips. By the time they arrived,
the server motherboards had been replaced with something better and
faster, so the new chips just sat around.

Microsoft products are so full of 'problems' that if they ever put out an
error free product it would seem to be a mistake.

I beg to differ. Microsoft bashing seems to be the national sport in
computers. Yet, they're the most successful computah company in
history. In addition, they did it without any ties to proprietary
hardware. They must be doing something right.

In my never humble opinion, 99% or more of what MS releases is done
correctly and works well. The 1% that doesn't is what we're all
complaining about. Because MS has such a huge number of products and
technologies, it's fairly easy to find bugs and problems. However, if
you compare the MS bug lists with those from other companies, the
ratio of bugs to product complexity is very favorable for MS products.
I have had to deal with OS's and apps from smaller companies. Methinks
they're far worse than MS. Also, there may be plenty to complain
about, but most products are sufficiently functional to be usable for
the intended purpose. What bothers me about MS is not the quantity of
bugs, it's their tendency to add features and functions instead of
fixing bugs. This tends to make the product grow into a bloated
monstrosity of useless features, with far too many semi-permanent
bugs.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

On Sat, 09 May 2009 19:32:57 -0700, Jeff Liebermann
wrote:

http://en.wikipedia.org/wiki/Pentium_FDIV_bug

Also, the Foof bug:
http://en.wikipedia.org/wiki/F00f


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

"Jeff Liebermann" wrote in message
...

I beg to differ. Microsoft bashing seems to be the national sport in
computers. Yet, they're the most successful computah company in
history. In addition, they did it without any ties to proprietary
hardware. They must be doing something right.


Microsoft got so big the same way Walmart did. They put out a cheeper
product.

Digital Research had a much beter product when IBM produced the PC. I think
they wanted about $ 150 for it and MS wanted $ 50 for their product. They
basically put DRI out of business and also some other companies that had
their ideas incorporated in to the MS product line.

On Sat, 9 May 2009 22:51:37 -0500, "Ralph Mowery"
wrote:


"Jeff Liebermann" wrote in message
.. .

I beg to differ. Microsoft bashing seems to be the national sport in
computers. Yet, they're the most successful computah company in
history. In addition, they did it without any ties to proprietary
hardware. They must be doing something right.


Microsoft got so big the same way Walmart did. They put out a cheeper
product.

They weren't always the biggest and baddest company in town. The
software departments of the major big iron makers were much larger
than MS in both manpower and revenue for most of the 1980's. Any one
of them could have produced a consumer grade operating system and
usable apps at the time and wiped MS off the map. They didn't because
they didn't believe that there was money to be made in essentially
consumer retail (i.e. off the shelf) operating systems and apps. They
also didn't know how to do it. I still recall the DEC Rainbow, where
customers were expected to buy pre-formatted floppies from DEC at
outrageous prices.

MS may also be very economical for OEM PC operating systems and
desktop apps. However, I note that a superior and totally free
operating system, while quite popular, has not produced much of a dent
in Microsoft's OS dominance. MS is also not currently the cheapest
OS. Apple OS/X Leopard retails for $130 while Vista Ultimate is $219.
Digital Research had a much beter product when IBM produced the PC.
I think
they wanted about $ 150 for it and MS wanted $ 50 for their product. They
basically put DRI out of business and also some other companies that had
their ideas incorporated in to the MS product line.

Yep. In 1981, CP/M-86 was better than PC-DOS 1.0. I was there.
CP/M-86 sold for $150. PC-DOS 1.0 sold for $60. Most of the early
IBM PC 5150 adopters bought both. I vaguely recall paying about
$4,000 for mine. $100 difference wasn't going to make a huge
difference.

CP/M-86 did more, but was more difficult to use. PC-DOS (er... QDOS)
was crude and simple. At the time everyone was waiting for DRI to
clean up the OS or at least make it more user friendly, while PC-DOS
was treated as a temporary expedient so IBM could sell PC's that were
suppose to run mostly apps in BASIC. Also note that PC-DOS included
MSBASIC, while CP/M-86 would sorta run the older CP/M-80 apps. CBASIC
came later. The IBM PC 5150 came with cassette BASIC in ROM. However
BASIC in ROM was not easily accessible from CP/M-86. Within months of
introduction, there were literally hundreds of new and ported apps for
PC-DOS arriving at Computerland. Meanwhile CP/M-86 was still
struggling with porting CP/M-80 apps. I had customers running some
bookkeeping application on CP/M-86 well into the late 1980's. It was
a struggle under CP/M-86. When they finally purged the machines and
switched to PCDOS, things went more smoothly. For example, relinking
the CP/M-86 operating system to install a new device driver was not my
idea of fun. With PC-DOS, it was just adding a line in config.sys.

All this has something to do with ham radio antennas, but the
connection escapes me for the moment.






--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
Yep. In 1981, CP/M-86 was better than PC-DOS 1.0. I was there.

I was there also. Some of the future CP/M-80 guys
worked for Intel while I was there. They tried to
get Intel to develop their ISIS-80 software
development system program into an open architecture.
Intel decided most of the money to be made was in the
hardware chips and that there was not much money to be
made in microcomputer operating systems and computer
boxes.

Those high-caliber software guys moved from Silicon Valley
to Digital Research over on the Pacific coast and the rest
is history. Intel could have been the behemoth supplying
the microcomputer chips, operating system, AND the
computer box.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

"Ralph Mowery" wrote:

Microsoft got so big the same way Walmart did. They put out a
cheeper product.


What cheaper product was that? After CP/M and similar OS's died
decades ago, the earlier PC-DOS and later Windows were the only
commercially distributed OS's available unbundled from hardware. Thus,
Windows really had no significant competing product to be cheaper
than. The hardware to run those Microsoft OS's was occasionally
cheaper, but Microsoft had no great influence in that.

stewart / w5net

"noname" wrote in message
...
"Ralph Mowery" wrote:

Microsoft got so big the same way Walmart did. They put out a
cheeper product.


What cheaper product was that? After CP/M and similar OS's died
decades ago, the earlier PC-DOS and later Windows were the only
commercially distributed OS's available unbundled from hardware. Thus,
Windows really had no significant competing product to be cheaper
than. The hardware to run those Microsoft OS's was occasionally
cheaper, but Microsoft had no great influence in that.

stewart / w5net

The very first operating systems were either DR or MS products. MS was
cheeper than the DR product.
Then MS incorporated softwear like Double Space (big lawsuit over that so
win 3.11 came out ) Internet explorer is standard now. Pushed out many
other internet programs.