Hi . what is the difference between numel() and length() of a given vector ?

what is the difference between numel() and length() of a given vector ?

Answer 1

[KSSV]

numel gives you total number of elements present in the array. i.e. it is product of result of size function.

A = rand(10,3) ; 
numel(A)

ans = 30

size(A,1)*size(A,2)

ans = 30

length gives you maximum number of size or which ever is dominant along row and column.

A = rand(10,3) ;
length(A)

ans = 10

size(A,1)

ans = 10

%
B = A' ;
length(B)

ans = 10

size(B,2)

ans = 10

[Stephen23]

Indeed, LENGTH gives the size along the longest dimension, but not just rows or columns:

length(nan(2,3,4))

ans = 4

I have never seen anyone actually make use of this "feature".

[KSSV]

@Stephen yes...good point..forgot to consider multi dimensions.