Getting Started |
Other Data Structures
This section introduces you to some other data structures in MATLAB, including
Multidimensional arrays in MATLAB are arrays with more than two subscripts. One way of creating a multidimensional array is by calling zeros
, ones
, rand
, or randn
with more than two arguments. For example,
creates a 3-by-4-by-5 array with a total of 3x4x5 = 60 normally distributed random elements.
A three-dimensional array might represent three-dimensional physical data, say the temperature in a room, sampled on a rectangular grid. Or it might represent a sequence of matrices, A(k), or samples of a time-dependent matrix, A(t). In these latter cases, the (i, j)th element of the kth matrix, or the tkth matrix, is denoted by A(i,j,k)
.
MATLAB and Dürer's versions of the magic square of order 4 differ by an interchange of two columns. Many different magic squares can be generated by interchanging columns. The statement
generates the 4! = 24 permutations of 1:4
. The k
th permutation is the row vector p(k,:)
. Then
stores the sequence of 24 magic squares in a three-dimensional array, M
. The size of M
is
computes sums by varying the d
th subscript. So
is a 1-by-4-by-24 array containing 24 copies of the row vector
is a 4-by-1-by-24 array containing 24 copies of the column vector
adds the 24 matrices in the sequence. The result has size 4-by-4-by-1, so it looks like a 4-by-4 array.
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