Subject: Re: Equation Editor. (fwd)
From: Karl Ove Hufthammer (huftis@bigfoot.com)
Date: Tue Sep 05 2000  11:41:44 CDT
 Original Message 
From: "Caolan McNamara" <cmc@stardivision.de>
To: "Karl Ove Hufthammer" <huftis@bigfoot.com>
Cc: <abiworddev@abisource.com>
Sent: Tuesday, September 05, 2000 5:04 PM
Subject: Re: Equation Editor. (fwd)
 At 16:16 05.09.00 +0200, Karl Ove Hufthammer wrote:
 >One solution I would like for an AbiWord equation editor is a way to create
 >*good* content MathML using a "verbal" language. One program which uses
 >this is
 >Dave Raggett's (the editor of the HTML specification) EZMath. Here you write
 >mathematics like you would speak it, and it outputs (good) content MathML.
 >
 >The quadratic formula:
 >x = {b plus or minus sqrt {b^2  4ac}}/2a

 Well you'll like starmath then, the starmath equivalent is...
 x = {b plusminus sqrt {b^2  4ac}}/2a
Looks good ...
 Where I think it falls down is that with grouping you cannot easily see
 which {
 is with },
Syntax colouring. Make the outer {}s (i.e. the ones directly outside the cursor)
bold.
 the standard programming problems apply, and as the equation
 gets larger
 and matrices and other more verbose constructs make their appearance it gets
 difficult very fast, Nevertheless these are visual interface issues,
 primarily I
 am concerned with the file formats under the hood of all this.
If the equation/formula is entered as 'x=a+b', there's really no reason to save
it as MathML:
<math>
<reln>
<eq/>
<ci>y</ci>
<apply>
<plus/>
<ci>a</ci>
<ci>b</ci>
</apply>
</reln>
</math>
But it should of course be possible to convert it to MathML (e.g. for exporting
into XHTML+MathML).
 The starmath UI
 interface will remain but the native format will hopefully move to MathML,
 Ill have
 a bit of a think during the implementation about preserving closer the
 users intent
 when importing from visual based ones.

 >Trigonometrical functions:
 >sin {2x} = 2 sin x times cos x
 sin {2x} = 2 sin x times cos x

 Certainly theres a similarity,
:)
 perhaps a similar root interface is behind both
 apps.

 >Limits:
 >{limit as x tends to infinity of integral from 0 to x wrt y of e^y^2} =
 >sqrt pi
 >/ 2

 This is probably,
 lim csup {x rightarrow infinity} int from 0 to x y(e^{y^2} )} = sqrt pi / 2
The EZMath approach seems more natural here. StarMath seems more visually
oriented ('righarrow').
 though this is more limited because I personally don't construct math
 verbally,
 seems like we need a "tends" word.
Well, in EZMath, you can write things in *several* ways. Example:
x to the power of 3
x cubed
x^3
are all equal.
 Isn't there though some issues as to
 peoples
 languages ?, this language isn't localized as far as I know in StarMath,
 its always
 pseudo english, and at even from my (native speaker) perspective some of the
 terminology is different even from what I would use, though thats more likely
 a personal thing.
You raise an important point here. Localizability would certainly be very nice.
It's easy if the syntax is similar (as in Spanish), but can be difficult to
localize into some other languages. Anyway, it should always be stored in
English (or MathML).
 So a graphical interface would negate some of those issues.
But would introduce other problems (mainly concerning *meaning* which is
necessary for using MathML). Though I don't think it's impossible to constuct a
graphical (point and click) interface ...
 Karl Ove Hufthammer
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