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Packed Arrays: An Efficient Internal Storage Format in Mathematica 4

Rob Knapp
Organization: Wolfram Research, Inc.
Department: Kernel Technology

While packed arrays may sound quite mysterious and deep, the idea is really quite simple. When it is clearly appropriate to represent a list of a single type machine numbers (integer, real, or complex) internally as an array, Mathematica does so. The basic technology is actually there in Mathematica 3.0, and is visible in the List operations that were added to the compiler. Basically what has been done for Mathematica 4 is to extend this representation to kernel functions where it is appropriate. The internal representation is essentially invisible to you as a user (you have to use functions in the Developer` context to even see it) so you do not have to worry about it. However, understanding the packed array representation can help you write faster, more memory-efficient code.

*Wolfram Technology > Kernel > Data Structures

LU Decomposition, Data representation, Listable operations, structural operations, internal array format, packed array
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*Packed Arrays: An Efficient Internal Storage Format in Mathematica 4   [in Articles]
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PackedArrays.nb (43.9 KB) - Mathematica Notebook