IDL provides a variety of mechanisms for working with multidimensional data sets. Understanding these mechanisms requires a familiarity with linear algebra and the concept of a two-dimensional data set. Consider a two-dimensional data set, with dimensions m and n. In a computer, the data from this data set is stored in a unidimensional set of memory addresses; what makes the data "two-dimensional" is the way the individual elements are indexed by the software that accesses the data in memory. This topic is discussed in detail in Columns, Rows, and Array Majority; if you are unsure of your understanding of the process of mapping multidimensional data into unidimensional computer memory, please read that section carefully.
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