With cell arrays you have two methods of indexing namely parenthesis (i.e. (...)) and braces (i.e. {...}).

Lets create a cell array to use for examples:

A = {3,   9,     'a'; 
     'B', [2,4], 0};

Indexing using paranthesis returns a portion of the cell array AS A CELL ARRAY. For example

A(:,3)

returns a 2-by-1 cell array

ans =

    'a'
     0

Indexing using braces return the CONTENTS of that cell, for example

A{1,3}

returns a single character

ans =

a

You can use parenthesis to return a single cell as well but it will still be a cell. You can also use braces to return multiple cells but these return as comma separated lists, which is a bit more advanced.

When assigning to a cell, very similar concepts apply. If you're assigning using parenthesis, then you must assign a cell matrix of the appropriate size:

A(:,1) = {1,1}

if you assign a single value using parenthesis, then you must put it in a cell (i.e. A(1) = 2 will give you an error, so you must do A(1) = {2}). So it's better to use braces as then you are directly affecting the contents of the cell. So it is correct to go

A{1} = 2

this is equivalent to A(1) = {2}. Note that A{1} = {2}, which is what you've done, will not give a error but what is does is nests a cell within your cell which is unlikely what you were after.

Lastly, if you have an matrix inside one of your cells, then Matlab allows you to index directly into that matrix like so:

A{2,2}(1)

ans = 

     3

Hi Jim, Remember that cell arrays can hold arbitrary data (including other cell arrays) and that while [] is concatenate, {} is "build a cell array". From the documentation about {}: "Braces are used to form cell arrays. They are similar to brackets [ ] except that nesting levels are preserved." Therefore, after your fourth assignment to legends, you actually have a cell array containing two elements, a cell array and a string. Instead, consider using: >> legends = {'first'} legends = 'first' >> legends(end+1) = {'second'} legends = 'first' 'second' >> legends(end+1) = {'third'} legends = 'first' 'second' 'third' Even better yet, if you know all the strings ahead of time, generate it all at once such as: legends = {'first' ... 'second' ... 'third'} legends = 'first' 'second' 'third' todd

Is there any reason why basic math operations don't work with cell arrays? Seems to me it would extremely useful and efficient if you could do the following: Cell arrays are designed for containing objects of different types and sizes. They are a fundamentally inefficient way to hold objects that are all the same size, partly because their contents are not guaranteed to be held contiguously in RAM. Because a better data type is usually available for the situations you describe, TMW hasn't bothered to define such operations for cells. You could write cell-like class with overloaded arithmetic operations if you wished, but it would be syntactic sugar, and nothing more. For the scenario in your example, moreover, the best method is in any case a simple for loop. This accomplishes the whole operation with just 3 multiplications with A, unlike the approach you presented which first forms Apow. out=cell(1,4); out{1}=C; for i=2:4 out{i}=out{i-1}*A; end out=out(2:end);