d = size(X)
[m,n] = size(X)
m = size(X,dim)
[d1,d2,d3,...,dn] = size(X),
[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:
di equals the size of the ith dimension of X for 0<i<n, but dn equals the product of the sizes of the remaining dimensions of X, that is, dimensions n through ndims(X).
size returns ones in the "extra" variables, that is, those corresponding to ndims(X)+1 through n.
The size of the second dimension of rand(2,3,4) is 3.
m = size(rand(2,3,4),2) m = 3
Here the size is output as a single vector.
d = size(rand(2,3,4)) d = 2 3 4
Here the size of each dimension is assigned to a separate variable.
[m,n,p] = size(rand(2,3,4)) m = 2 n = 3 p = 4
If X = ones(3,4,5), then
[d1,d2,d3] = size(X) d1 = d2 = d3 = 3 4 5
But when the number of output variables is less than ndims(X):
[d1,d2] = size(X) d1 = d2 = 3 20
The "extra" dimensions are collapsed into a single product.
If n > ndims(X), the "extra" variables all represent singleton dimensions:
[d1,d2,d3,d4,d5,d6] = size(X) d1 = d2 = d3 = 3 4 5 d4 = d5 = d6 = 1 1 1