WebMath: standard notation for negative numbers? ALT 0150

[Douglas Butler]

> In a web page where you are faking the math,
> you are probably stuck using hyphen minus.

Not so - ANY font has a proper minus sign (en-dash) which can be inserted
anywhere as ALT 0150  eg –x (better than -x), though the distinction will
only be seen in this email if you are running in formatted text.

Likewise ALT 1076 for 45°, and ALT 0178 for x², and ALT 0179 for x³

VERY annoying that IE6 does not recognise the Unicode font extensions -
that single advance would solve 50% of MATH notation problems on the Web,
ie all math expressions that can be written as a single line of text.

-- 
Douglas Butler
iCT Training Centre (Oundle School), PO Box 46, Peterborough PE8 4JX, UK
Tel: +44 1832 273444  Fax: +44 1832 272760
www.argonet.co.uk/oundlesch  www.autograph-math.com
-----------------------------------------------------------


-- Your message . .Robert Miner--
>
> Hi.
>
>> Is there an international standard in notation for negative numbers?
>> One  enquirer has asked:
>>
>> "Personally, I have been brought up differentiating between 'negative
>> seven'  and 'subtract seven' through the former being a 'raised' sign
>> compared with the  subtraction sign.  However, is this 'standard'
>> world-wide or is there no agreed  standard?  I note on several web
>> sites that often a raised sign is not used for  'negative' and a
>> 'subtraction' sign is used instead.  However, I don't know  whether
>> that is because that is standard in that country or whether they are
>> just being 'lazy' (also, of course, the issue of computers may make
>> people not  bother using a raised sign as it is not as easy to produce
>> on a computer as a  standard subtraction sign).  Of course, it may
>> well be the case that there is  no standard at all."
>
> My take on this is that the "raised" minus sign is mostly a
> pedagogical convention.  I thrives in the world of handwritten
> mathematics, but is rare in typeset mathematics.
>
> In Unicode 3.2 (which is the newest version which include several
> thousand new characters for math) there are a couple relevant
> charaters:
>
> 0x002d (45)	HYPHEN-MINUS
> 0x2122 (8482)   MINUS SIGN
>
> Typically in fonts, the hyphen minus (which is the one on the
> keyboard) is shorter, thicker, and sometimes a little raised.  The true
> minus is the longer, thinner more TeX-like symbol.
>
> In a web page where you are faking the math, you are probably stuck
> using hyphen minus.  But in most math typesetting software, including
> the main MathML implementations, usually a hyphen minus in math markup
> is interpreted as being the true minus as a convenience.  Obviously
> that works against using the hyphen minus as a stand in for the
> "raised minus", but since that doesn't work dependably anyway that's
> probably not a bad thing.
>
> To get a dependable, clearly different raised minus, I would use a
> regular minus as a superscript to an space or something like that.
>
> My own view of the standard way of distinguishing the
> unary minus from the binary minus operator is that this is done with
> spacing, at least in typeset math.  A unary minus operator (the kind
> that you get with negative numbers) is sucked up close to its operand
> on the right, while the binary minus has fairly generous spacing on
> both sides: -2 vs 2 - 3.  When there's ambiguity, I think most typeset
> texts would use parens 2 - (-3), etc.
>
> --Robert
>
> ------------------------------------------------------------------
> Robert Miner                                    RobertM at dessci.com
> MathML 2.0 Specification Co-editor                    651-223-2883
> Design Science, Inc.   "How Science Communicates"   www.dessci.com
> ------------------------------------------------------------------



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