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Array dimensions



d = size(X) returns the sizes of each dimension of array X in a vector d with ndims(X) elements. If X is a scalar, which MATLAB regards as a 1-by-1 array, size(X) returns the vector [1 1].

[m,n] = size(X) returns the size of matrix X in separate variables m and n.

m = size(X,dim) returns the size of the dimension of X specified by scalar dim.

[d1,d2,d3,...,dn] = size(X), for n > 1, returns the sizes of the dimensions of the array X in the variables d1,d2,d3,...,dn, provided the number of output arguments n equals ndims(X). If n does not equal ndims(X), the following exceptions hold:

n < ndims(X)

di equals the size of the ith dimension of X for , but dn equals the product of the sizes of the remaining dimensions of X,that is, dimensions n through ndims(X).

n > ndims(X)
size returns ones in the "extra" variables, that is, those corresponding to ndims(X)+1 through n.


Example 1. The size of the second dimension of rand(2,3,4) is 3.

Here the size is output as a single vector.

Here the size of each dimension is assigned to a separate variable.

Example 2. If X = ones(3,4,5), then

But when the number of output variables is less than ndims(X):

The "extra" dimensions are collapsed into a single product.

If n > ndims(X), the "extra" variables all represent singleton dimensions:

See Also

exist, length, numel, whos

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