DataSize:

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   Find the size in bytes of a piece of data.

   Doubles are assigned 8 bytes.
   Integers are assigned 4 bytes.
   Characters are assigned 4 bytes.

   A number is treated as an integer only if it is a whole number. In the case
   of numeric arrays, the following rules are applied. These rules are
   consistent with the C++ matrix library.
     * For 2-D arrays, all elements are considered to be doubles.
     * For 1-D arrays, if any element is not a whole number, then all of
       the elements are treated as doubles.

   Since version 7.
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   Form:
   ds = DataSize( data, runningSize )
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   ------
   Inputs
   ------
   data             (.)      A piece of data. The following types are supported:
                                - single numbers and numeric arrays (up to 2-D)
                                - single characters and character arrays (up to 2-D)
                                - single structures and structure arrays (up to 2-D)
                                - single cells and cell arrays (up to 2-D )

   runningSize      (1)      The size of data already computed. Used for 
                             recursive implementation of this function.

   -------
   Outputs
   -------
   ds               (1)      Size of the supplied data, in bytes

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