6.2.4. The gridded table definition element

The griddedTableDef element defines a multi-dimensional table of values corresponding with the value of an arbitrary function at each intersection of a set of specified independent input values. The coordinates along each dimension are defined in separate breakpointDef elements that are referenced within this element by bpRefs, one for each dimension.

The data contained within the data table definition are a comma- or white space-separated set of floating-point values. This list of values represents a multi-dimensional array whose size is inferred from the length of each breakpoint vector. For example, a 2D table that is a function of an eight-element Mach breakpoint set and a ten-element angle-of-attack breakpoint set is expected to contain 80 (8 x 10) comma- or white space-separated values.

By convention, the breakpointRefs are listed in order such that the last breakpoint set varies most rapidly in the associated data table listing. See Section 6.5.1, “Point order” below.

An optional uncertainty element may be provided that represents the statistical variation in the values presented. See Section 6.4 for more information about this element.

    griddedTableDef : gtID, [name, units]
          {description of table in character data}
            provenanceRef? : provID
            provenance? : [provID]
                author+ : name, org, [email]
                    contactInfo* : [contactInfoType, contactLocation]
                        {text describing contact information}
                creationDate : date {in YYYY-MM-DD format}
                documentRef* : [docID,] refID
                modificationRef* : modID
        breakpointRefs :
            bpRef+ : bpID
        uncertainty? : effect
            (normalPDF : numSigmas | uniformPDF)
            {character data of comma- or white space-separated table values}


griddedTableDef attributes:


An internal reference that is unique within the file.


A UNICODE name for the table (may be the same string as gtID).


The units-of-measure of the table's output signal. See Section 6.5.6, “Units” below.

griddedTableDef sub-elements:


The optional description element allows the author to describe the data contained within this griddedTable.


The optional provenance element allows the author to describe the source and history of the data within this griddedTable. Alternatively, a provenanceRef reference can be made to a previously defined provenance.


The mandatory breakpointRefs element contains separate bpRef elements, each pointing to a separately defined breakpointDef. Thus, the independent coordinates associated with this function table are defined elsewhere and only a reference is given here. The order of appearance of the bpRefs is important; see the text above.


This optional element, if present, describes the uncertainty of this parameter. See Section 6.4 for more information about this element.


The numeric values of the function at the function vertices specified by the breakpoint sets are contained within this element, in a single comma- or white space-separated list, representing an unraveled multi-dimensional table. Parsing this list and storing it in the appropriate array representation is up to the implementer. By convention, the last breakpoint value increases most rapidly.

Example 8.  An excerpt showing an example of a griddedTableDef element

This nonlinear function table is used by a subsequent function in Example 11 to specify an output value based on two input values: body flap deflection and Mach number. This table is defined outside of a function element because this particular function table is used by two functions: one for the left-lower body flap and one for the lower-right body flap; thus, their actual independent (input) variable values might be different.

        <!-- ==================================== -->     1
        <!-- Lower Body Flap Tables (definitions) -->
        <!-- ==================================== -->

  <griddedTableDef name="CLBFL0" gtID="CLBFL0_table">     2
    <description>      3
        Lower body flap contribution to lift coefficient,
        polynomial constant term
    <provenance>        4
      <author name="Bruce Jackson" org="NASA Langley Research Center" email="[email protected]"/>
      <creationDate date="2003-01-31"/>
      <documentRef docID="REF01"/>
    <breakpointRefs> 5
      <bpRef bpID="DBFL_PTS"/>
      <bpRef bpID="XMACH1_PTS"/>
    <dataTable> <!-- last breakpoint (XMACH) changes most rapidly --> 6
<!-- CLBFL0 POINTS  -->
<!-- DBFL =        0.0       -->
 0.00000E+00 , 0.00000E+00 , 0.00000E+00 , 0.00000E+00 , 0.00000E+00 ,
 0.00000E+00 , 0.00000E+00 , 0.00000E+00 , 0.00000E+00 , 0.00000E+00 ,
 0.00000E+00 , 0.00000E+00 , 0.00000E+00 ,
<!-- DBFL =       15.0       --> 7
-0.86429E-02 ,-0.10256E-01 ,-0.11189E-01 ,-0.12121E-01 ,-0.13520E-01 ,
-0.86299E-02 ,-0.53679E-02 , 0.76757E-02 , 0.11300E-01 , 0.62992E-02 ,
 0.51902E-02 , 0.38813E-02 , 0.37366E-02 ,
<!-- DBFL =       30.0       -->
 0.22251E-01 , 0.26405E-01 , 0.28805E-01 , 0.31206E-01 , 0.34806E-01 ,
 0.31321E-01 , 0.28996E-01 , 0.19698E-01 , 0.18808E-01 , 0.12755E-01 ,
 0.10804E-01 , 0.98493E-02 , 0.83719E-02 ,
<!-- DBFL =       45.0       -->
   . [other points in table]

Comments are good practice for human readers


name is used for documentation purposes; gtID is intended for automatic wiring (autocode) tools.


Descriptions make for good practice whenever possible. Here we explain the contents of the function represented by the data points.


provenance is the story of the origin of the data.


These bpRefs are in the same order as the table is wrapped (see text above) and must be reflected in the referencing function in the same order. In this excerpt, the referencing function must list the independentVarRefs such that the signal that represents delta body flap (DBFL) must precede the reference to the signal that represents Mach number (XMACH).


The points listed within the dataTable element are given as if the last bpRef varies most rapidly. See the discussion above.


Embedded comments are a good practice.