RTableDataBlock - Maple Help
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RTableDataBlock

access the rtable data in external code

 Calling Sequence RTableDataBlock(kv, rt)

Parameters

 kv - kernel handle returned by StartMaple rt - Maple rtable object

Description

 • These functions are part of the OpenMaple interface to Microsoft Visual Basic.
 • The RTable*DataBlock family of functions return a 1-D copy of the data contained in rt. Modifying the returned data does not change the original rtable. The RTable*DataBlock function called must match the datatype of the rtable, which can be obtained from the data_type field of the RTableSettings structure returned by RTableGetSettings.
 • The specific RTableDataBlock function returns the address of the actual memory used by Maple to store the rtable data.  This can be used to copy a changed data-block back and so update the rtable in Maple memory space.
 • The DoubleRTableDataBlock command provides a way to get the data of a datatype=float[8] rtable in a native 2-D or 3-D Visual Basic format.  A 2-D array returned can then be indexed via 2-D A(i,j) indexing instead of computing the equivalent A((j-1)*m+i-1) index into a 1-D array. In this case (i,j) will match the Maple index, usually starting at (1,1), whereas RTableF64DataBlock will always be offset from (0).
 • The data block of an rtable with an indexing function may not exactly match the way the data looks when viewed from Maple. For example, the data stored in position [1,1] of an rtable with a special indexing function may not correspond to the (0) element accessed from the rtable.
 • An error is raised if an attempt is made to get the data block from a Maple-sparse rtable.

Examples

 Public Sub MySumElems(ByVal kv As Long) Dim rts As RTableSettings Dim rt As Long Dim val As Double Dim i As Long ' original rtable rt = EvalMapleStatement(kv, "Matrix([[1,2,3],[4,5,6]],datatype=float[8]);") ' ensure float[8] datatype before choosing DataBlock function RTableGetSettings kv, rts, rt If rts.data_type = RTABLE_FLOAT64 Then n = RTableNumElements(kv, rt) ReDim data(0 To n - 1) As Double data = RTableF64DataBlock(kv, rt) ' sum all the elements in rt val = 0 For i = 0 To n - 1 val = val + data(i) Next i Write #1, "sum = ", val End If End Sub