NUMEL Number of Elements in an Array

Section: Inspection Functions

Usage

Returns the number of elements in an array x, or in a subindex expression. The syntax for its use is either 
   y = numel(x)

or 

   y = numel(x,varargin)

Generally, numel returns prod(size(x)), the number of total elements in x. However, you can specify a number of indexing expressions for varagin such as index1, index2, ..., indexm. In that case, the output of numel is prod(size(x(index1,...,indexm))).

Example

For a 4 x 4 x 3 matrix, the length is 4, not 48, as you might expect, but numel is 48. 
--> x = rand(4,4,3);
--> length(x)

ans = 
 4 

--> numel(x)

ans = 
 48

Here is an example of using numel with indexing expressions. 

--> numel(x,1:3,1:2,2)

ans = 
 6