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Subsections

NUMEL Number of Elements in an Array

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 = 
  <uint32>  - size: [1 1]
            4  
--> numel(x)
ans = 
  <int32>  - size: [1 1]
            48

Here is an example of using numel with indexing expressions.

--> numel(x,1:3,1:2,2)
ans = 
  <int32>  - size: [1 1]
             6


Samit K. Basu 2005-03-16