WebMath: standard notation for negative numbers? ALT 0150

[Robert Miner]

Hi.

You wrote:

> 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.

No.  en-dash is en-dash. The unicode point for MINUS in x2212.  You
can use an en-dash, but in my view, that is faking it.  

I concede that it sounds like using en-dash works pretty well though,
since as you say, en-dash is in pretty much any font that covers
ISO-LATIN-1, and usually looks the way you want.  I don't actually
object to "faking it" in the least, but I want to clarify the purist
viewpoint

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

I like the ALT xxxx trick too.  But note that that behavior is tied to
the authoring tool.  Not all authoring tools support it.

> 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.

I'm not sure what you mean by this.  Windows in general, and IE in
particular do have pretty good Unicode support, at least in my
experience.  What is lacking is Unicode encodings for fonts.  All
older fonts and most new ones use a different encoding scheme.  So if
you ask a random font for the glyph in slot x2212, you usually get
junk.

As an illustration, here are two snippets on HTML code where the code
points for hyphe en-dash and MINUS are hard coded as numerical escape
sequences. The first displays fine for me, since Lucida Sans Unicode
is one of the few widely distributed fonts with a Unicode encoding.
Note that the Lucida designers have made hypen and en-dash very
similar, but MINUS still looks like a minus sign.

However, in the second example, the first two come out fine, but the
third code point is a little bullet thing.  This is because Times in
not a Unicode-encoded font.

<div style="font-family: Lucida Sans Unicode">
Here is a hyphen &#45; and an en-dash &#150; and a minus &#x2212;
</div>

<div style="font-family: Times">
Here is a hyphen &#45; and an en-dash &#150; and a minus &#x2212;
</div>


--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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