Shown below are schematic overviews of the various elements currently available in
DAVEfunc
. Each element is described in detail in Section 8, “Element references and descriptions” later in this document. The following key is used to describe the
elements and associated attributes.
Key: elementname : mandatory_attributes, [optional_attributes] mandatory_single_sub-element optional_single_sub-element? {editorial comment} ( choice_1_sub-element | choice_2_sub-element ) zero_or_more_sub-elements* one_or_more_sub-elements+ (character data) implies UNICODE text information
The
DAVEfunc
element has six possible sub-elements:
DAVEfunc : fileHeader variableDef+ breakpointDef* griddedTableDef* ungriddedTableDef* function* checkData?
DAVEfunc
sub-elements:
fileHeader
This mandatory element contains information about the origin and development of this model.
variableDef
Each DAVEfunc
model must contain at least one signal path (such as
a constant output value). Each input, output or internal signal used by the model must
be specified in a separate variableDef
.
A signal can have only a single origin (an input block, a calculation, or a function output) but can be used (referenced) more than once as an input to one or more functions, signal calculations, and/or as a model output.
In DAVE-ML 2.0, all signals are real and scalar.
The variableDef
s should appear
in calculation order; that is, a variableDef
should not appear
before the definitions of variables upon which it is dependent. This is good practice
since doing so avoids a circular reference. If a variable depends upon the output
(dependentVar
) of a function
it can be assumed
that dependence has been met, since function definitions appear later in the
DAVEfunc
element.
breakpointDef
A DAVEfunc
model can contain zero, one, or more breakpoint set
definitions. These definitions can be shared among several gridded function tables.
Breakpoint definitions can appear in any order.
griddedTableDef
A DAVEfunc
model can contain zero, one, or more gridded nonlinear
function table definitions. Each table must be used by multiple function
definition if desired for
efficiency. Alternatively, some or all
function
s in a model can specify their tables internally
with an embedded griddedTableDef
element.
A gridded function table contains dependent values, or data points, corresponding to the value of a function at the intersection of one or more breakpoint sets (one for each dimension of the table). The independent values (coordinates or breakpoint sets) are not stored within the gridded table definition but are referenced by the parent function. This allows a function table to be supported by more than one set of breakpoint values (such as left- and right-aileron deflections).
ungriddedTableDef
A DAVEfunc model can contain zero, one, or more ungridded nonlinear function table
definitions.
Unlike a rectangularly gridded table, an ungridded table specifies data
points as individual sets of independent and dependent values. Each table must be used
by at least one but can be used by multiple function
definitions if necessary
for efficiency. Alternatively, function
s can retain their tables
internally with a ungriddedTable element without sharing the table values with other
functions.
Ungridded table values are specified as a single (unsorted) list of independent
variable (input) values and associated dependent variable (output) values. While the
list is not sorted, the order of the independent variable inputs is important and must
match the order given in the parent function
. Thus, functions that
share an ungridded table definition must have the same ordering of independent variables.
The method of interpolating the ungridded data is not specified.
function
A function
ties together breakpoint
sets (for gridded-table nonlinear functions), function values (either internally or by
reference to table definitions), and the input- and output-variable signal
definitions, as shown in Figure 1. Functions also include provenance, or background history, of the function data
such as wind tunnel test or other source information.
checkData
This optional element contains information allowing the model to be automatically verified after implementation by the receiving party.
An example of each of these sub-elements is given below. Complete descriptions of each element in detail are found in Section 8, “Element references and descriptions”.
2011-03-31