Hi 
I went a little crazy last night. Tooo little chocolate in last few days and
then had so much i passed out. Sorry about posts, especially to Regina.
More at bottom to answer Steve
Regards from
Tom 
From: Steve Edmonds <steve.edmonds@ptglobal.com>
To: documentation@global.libreoffice.org
Sent: Sat, 11 June, 2011 5:29:51
Subject: Re: [libreoffice-documentation] Re: Collecting small things in the
Wiki
> Hi 
>
> Regina, this is not a criticism of you but just some of my anger at the
world
> that gave me a fairly decent education in sciences and maths and made me
> practically unemployable as a result.
>
>
> Ok, again
>
> -3 x -3 = 9
>
> I think people tend to expect the - to make the result -9. Perhaps they
expect
> the result to be the same as -(3^2) which is a completely different thing.
> Again this is more about people lack of maths understanding than about
> spreadsheets. An evening course or on-line course about maths is the
answer,
> not documentation for a spreadsheet program.
>
>
> In the bug-report the first comment complains that spreadsheet programs
stick to
>
> internationally agreed maths standard for the order in which to apply
functions,
>
> Bodmas (stands for "Brackets, of/division, multiplication, add, subtract").
> Choosing a non-standards order makes higher functions exponentially
difficult or
>
> even impossible. Before the 0 was borrowed from Arabic notation simple
> multiplication and division was only possible by people with a university
degree
>
> level of maths skills. Choosing to go against Bodmas would be similarly
> catastrophic.
>
> Business users like to left align numbers which makes simple addition more
> difficult at a glance, for example
>
> £34
> £300
> ======
> £640 ?!!?
>
> Maths people and accountants tend to shudder at left aligned numbers, or
realise
>
> they are likely to make a lot of cash from these people. A right-justified
list
>
> makes it much more obvious
>
> £34
> £300
> =====
> £334 in a much more obvious way. Ok, its a stupid example with only 2
numbers
> in the list but imagine with a LOT more numbers in the list, say 20 to 30
per
> page.
>
>
> Back to the expected result of -9. What is the square root? -3 x 3 is not
> really right. In fact we are now getting towards 2 dimensional numbers
such as
> "imaginary numbers" and perhaps even getting close to chaos theory and
fractal
> dimensions.
>
>
> In the bug-report the first post shows a stunning lack of understanding
about
> maths, roughly along the lines of demanding that the spreadsheet program
should
> give £640 in my example of adding numbers.
>
>
> "
> I definitly see this as a bug and confirm it. Here's what I did:
>
> 1: Input "=-3^2+4" into a spreadsheet cell, result is 13
> 2: Input "=4-3^2" into another cell, result is -5
> 3: Input "=-(3^2)+4" into a third cell, result is -5
>
> The problem here seems to be that the program attaches the negative sign to
the
> 3 in step one before doing the square, which it should not, unless
manipulated
> by parentheses like this: "(-3)^2".
> "
>
> In 1 the result is 13 because the first function done is -3 x -3 = 9, and
then
> add the 4 to give 13
> In 2 the result is due to an ambiguity that is normally resolved by using
the
> standards method of afaik 3 x 3 = 9, and then 4 - 9 = -5 People with maths
> skills generally realise there is a potential problem with the ambiguity
here
> and might try fixing it by using brackets eg = 4 + (-3^2) which gives us 13
> 'obviously' since the inside of the bracket is done before applying the
stuff
> outside the brackets.
>
> In 3 the result is -5 because the bracketed stuff is done first giving us +9
> again, then outside the bracket that is made -+9 = -9 and then the 4 is
added as
> expected.
>
>
> This is maths, not spreadsheet stuff, unless i made a mistake in how #2
should
> be treated according to the Bodmas standards (in which case the bug-report
needs
> to be fixed asap) but afaik i'm right. Even if i am wrong this is not
really a
> job for documentation except as a brief note that 'common-sense' sometimes
> over-rides Bodmas but will hopefully be fixed soon.
>
> Regards from
> Tom 
>
>
>
>
>
> ________________________________
> From: Regina Henschel <rb.henschel@t-online.de>
> To: documentation@global.libreoffice.org
> Sent: Fri, 10 June, 2011 23:39:01
> Subject: Re: [libreoffice-documentation] Re: Collecting small things in the
Wiki
>
> Hi Tom,
> Tom Davies schrieb:
>
>> Hi 
>> 3^2 does =9 ?
>>
> That's not the problem. But -3^2 result in 9 and that is the problem.
> http://openoffice.org/bugzilla/show_bug.cgi?id=26755
>
> Kind regards
> Regina
>
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>
Hi Tom.
I think it is bedmas - brackets, exponentiation, division,
multiplication, addition, subtraction.
There will be a mathematical standard for this, so I suppose we are
theorizing.
To remove all doubt, if you wanted (-3)^2 you would use the brackets
thus and if you wanted -(3^2) you would bracket that way. If there is no
"Standard" then may be with a leading '-' sign LO should ask or auto
correct to one of the bracketed options so it is clear what LO will do
with the number. I have always taken -3^3 = -27 same as LO does now, was
like that throughout university, but who is to say it is correct.
steve
Hi 
Yes the o in Bodmas doesn't make much sense and is not intuitive but i think
it's meant to mean "Orders" referring to orders, powers, indices & exponents,
NOT "omg not this again". In the US they don't have Brackets, they have
simplified it to Parenthesis so a common mnemonic there is Pedmas. Oh and they
simplified Exponents to Exponentiation along with dialogues to dialogz and
Catherine to Katz. I cheekily use tho instead of though but it hasn't kort-on
yet.
http://en.wikipedia.org/wiki/Order_of_operations#Mnemonics
Here are guides to show what level of maths we are talking about
http://www.primaryresources.co.uk/maths/mathsC3.htm
http://www.mathsisfun.com/operation-order-bodmas.html
Primary is about equivalent of Elementary in the US. It's from about 4 to about
12 with some regional variations of 1 year, ie sometimes 3 to 11.
The problem and ambiguity arise in computing because there is no difference
between - 1 and -1 in computers but in handwritten notes it is easier to
distinguish whether it is a value of (-1) or the value is (1) and then needs to
be subtracted from whatever precedes the -1 (such as the implied 0). There is a
note halfway down this page (or halfway up) about problems with computers and
calculators.
http://www.purplemath.com/modules/exponent5.htm
At school i was told-off for writing a 9 that looked like a 7. I tried to
explain that it was a 7 but that further annoyed the teacher who demanded that i
explain why it looked like a 9. There is just no arguing with some people.
I think that compatibility with Excel is important and i am not sure if we
should follow their way or the Internationally agreed standards as taught in
primary school (except to business people).
Regards from
Tom 