size

Array size

Usages

s = size(A)

• A is an array.
• It returns the size vector s of A.

[s1,s2,...,sn] = size(A)

• s1, s2, ..., sn are the lengths of the 1st, 2nd, ..., n-th dimensions of A.
• If the number of output arguments is larger than ndims, i.e., n > ndims(A), the output sd is equal to 1 for d equal to ndims(A) + 1, ..., n.
• If the number of output arguments is fewer than ndims, i.e., n < ndims(A), the last output sn is equal to the total number of elements in the remaining dimensions, i.e., size(A, n) * size(A, n + 1) * ... * size(A, ndims(A)).

sd = size(A, d)

• d should be a real positive integer.
• It returns sd, which is the length of the d-th dimension of A.
• If d exceeds ndims(A), then sd is 1.

Example

• This example demonstrates various usages of size().

Input

% Random vector
r = rand(1,2,3,4);

disp('Size vector')
vec = size(r)

disp('Num of outputs == ndims(r).')
[s1,s2,s3,s4] = size(r)

disp('Num of outputs > ndims(r). The extra output s5 is 1.')
[s1,s2,s3,s4,s5] = size(r)

disp('Num of outputs < ndims(r). s3 is equal to size(r,3) * size(r,4).')
[s1,s2,s3] = size(r)

Output

Size vector
vec = 
 1.0000   2.0000   3.0000   4.0000

Num of outputs == ndims(r).
s1 = 
 1.0000

s2 = 
 2.0000

s3 = 
 3.0000

s4 = 
 4.0000

Num of outputs > ndims(r). The extra output s5 is 1.
s1 = 
 1.0000

s2 = 
 2.0000

s3 = 
 3.0000

s4 = 
 4.0000

s5 = 
 1.0000

Num of outputs < ndims(r). s3 is equal to size(r,3) * size(r,4).
s1 = 
 1.0000

s2 = 
 2.0000

s3 = 
 12.000