This is a needed improvement to DAVE-ML.

My first thought is the arrayDef attribute should be something like 'dimensions="3"' and then a (set) of subelements that define the actual dimensions:

<arrayDef name="myDataMatrixr_m" varID="myDataMatrix" units="m" dimensions="3">
<description>My Data Matrix is a 2x6x3 matrix; the last dimension changes most rapidly</description>
111 112 113 <!-- the actual order is important, not the way the data is formatted -->
       121 122 123
       131 132 133
       141 142 143
       151 152 153
       161 162 163
<!-- second plane shows another valid way of listing a 6x3 matrix -->
       211 212 213 221 222 223 231 232 233 241 242 243 251 252
253 261 262 263 <!-- whitespace is unimportant -->

I also need to think through a way to mux and demux from scalars, and how well this fits into MathML matrix operations.

Have you guys been using this extension in any useful way?

Incidentally, the mailing list is getting rejections from several addresses, including yours:

A message addressed to [EMAIL PROTECTED] in distribution list "simstds" has been rejected.

I'm working on a new revision to the 2.0 release that will hopefully accompany the initial AIAA/ANSI Standard, but I don't think we'll be able to get arrays defined by then.

-- Bruce

On Mar 11, 2008, at 11:00 PM, Brian, Geoff wrote:

Hi all,

I am gauging for interest in adding the ability to define a data array element (such as a vector or n dimensional matrix) within the Dave-ML dtd. First thoughts would be to include an element like the "variableDef" maybe called "arrayDef" with attributes similar to the variableDef, but with additional attributes defining the dimensions for the array of data.

For example:

For a vector of size (4x1):
<arrayDef name="myDataVector_m" varID="myDataVector" units="m" dim1="4">

For a 2-D matrix of size (4x6):
<arrayDef name="myDataVector_m" varID="myDataVector" units="m" dim1="4" dim2="6">

For a n-D matrix of size (4x6x3x...):
<arrayDef name="myDataVector_m" varID="myDataVector" units="m" dim1="4" dim2="6" dim3="3" ...>

The data associated with the array would need to be either stored as a data table or computed using Math-ML expressions. It would also be useful if an element of an array could refer to a variableDef or another arrayDef (depending on the dimension of the array). I would expect that if arrays were manipulated using Math- ML then the interpreter (such as Janus) would need to manage the compatibility checking - that is outside the XML file.

One of the significant advantages of having an array element within Dave-ML would be the ability to encode matrix mathematics within the XML file - via Math-ML. I would find this particularly useful when processing axes transformation operations - eliminating the requirement for addressing the components individually. Another use would be the encoding of Inertia tensors and cg vectors as a single variable instead of having a variableDef for each component. I am sure there are many other uses.

I await in anticipations for comments on this proposal.

Geoff Brian

Aircraft Performance and Flight Dynamics
Air Vehicles Division
Defence Science and Technology Organisation

Ph: +61 (0) 3 9626 7318

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