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"

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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