How to use cell arrays ({})

Basically, cell arrays are arrays of arrays ;-)
Here's an example:

� z={rand(2),rand(3);rand(4),rand(5)}
z =
[2x2 double] [3x3 double]
[4x4 double] [5x5 double]
� z{1,1}
ans =
0.6813 0.8318
0.3795 0.5028

Arrays may be of different sizes and types. Especially useful are cell arrays to store text data:

� txt={'This is first string';'This is second'}
txt =
'This is first string'
'This is second'

Note that in order to store the same two strings in a normal array, you'd have to pad them to the same length!

Another very useful feature is that z{:} is always equivalent to comma separated list: "z{1},z{2},...". So you can use the cell array to pass parameters to a function...

� attrib={'p-','color',[.5 .1 .7],'linewidth',3};
� plot(x,y,attrib{:})
� legend(txt{:}); % in fact, you can omit {:} here

... or from a function:

� grid={[],[]}; contours={[],[]};
� [grid{:}]=meshgrid(0:10,0:10);
� grid{3}=grid{1}.*grid{2};
� [contours{:}]=contour(grid{:});
� clabel(contours{:})

Besides, you can easily convert a cell array to a normal one:

� z={[1,2],[3,4,5]}
z =
[1x2 double] [1x3 double]
� [z{:}] % again, equivalent to [z{1},z{2}] !
ans =
1 2 3 4 5

As you can see, it can be a very powerfull tool