From: Andrew Miller <ak.miller@auckland.ac.nz>

Date: Mon, 20 Nov 2006 12:03:52 +1300

Message-ID: <4560E2D8.30202@auckland.ac.nz>

To: "For those interested in contributing to the development of CellML." <cellml-discussion@cellml.org>

Cc: www-math@w3.org

Date: Mon, 20 Nov 2006 12:03:52 +1300

Message-ID: <4560E2D8.30202@auckland.ac.nz>

To: "For those interested in contributing to the development of CellML." <cellml-discussion@cellml.org>

Cc: www-math@w3.org

Hi all, I have been developing a plain-text input language for the content MathML in CellML documents (so that it can be efficiently edited by users). Although CellML is a declarative language rather than a procedural one, much of the expression syntax from languages like MATLAB and C-like languages can be re-used, and is likely to be familiar to many users. I have therefore tried to make my input language similar to these languages, where possible (for example, I have in-order operators like +, -, *, and / for plus, minus, times, divide, and a pre-order syntax, e.g. sin(x), for other operators). Please ask off-list for my bison grammar (a work in progress) if you would like to see it (I haven't checked it in to the public Subversion yet). Any opinions or suggestions on the overall structure of the language would be welcome. I am also seeking opinions on the most intuitive way to deal with the conversion between binary in-order operators like +. For example, if, within the input language, you have x = a + b + c + d + e + f a naive parser might create MathML like... <apply><eq/> <ci>x</ci> <apply><plus/> <apply><plus/> <apply><plus/> <apply><plus/> <apply><plus/> <ci>a</ci> <ci>b</ci> </apply> <ci>c</ci> </apply> <ci>d</ci> </apply> <ci>e</ci> </apply> <ci>f</ci> </apply> </apply> A slightly more complex parser might instead produce: <apply><eq/> <ci>x</ci> <apply><plus/> <ci>a</ci> <ci>b</ci> <ci>c</ci> <ci>d</ci> <ci>e</ci> <ci>f</ci> </apply> </apply> I would be interested in opinions on whether you feel this automatic translation from multiple binary in-order operators to a single pre-order operation makes sense (note: all CellML tools available now work with real numbers only, but future work could allow it to be extended to support other mathematical constructs. Using a definitionURL on an operator is technically valid CellML, but no tools can do anything with this either). The issue is complicated by what to do with bracketed expressions(which I currently allow, to override ambiguity). For example, a user could enter... x = (((((a + b) + c) + d) + e) + f) I would be interested to know if you believe that the first content MathML encoding or the second is more appropriate. Best regards, Andrew MillerReceived on Sunday, 19 November 2006 23:04:08 GMT

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