How to create an empty array in a matrix

Use the [] operator. Example:

x = [];

If you wanna be specific in the type of the empty matrix, use the empty property. Examples:

emptyDoubleMatrix = double.empty; % Same as emptyDoubleMatrix = [];
emptySingleMatrix = single.empty;
emptyUnsignedInt8Matrix = uint8.empty;

This works for empty matrices of classes as well. Example:

emptyFunctionHandleMatrix = function_handle.empty;

You can use the empty matrix/vector notation, [], and Matlab will set up a placeholder for it.

x = []

Now if you want to append a scalar, say num, to it, you cannot index it because it is empty.

However, you can either:

1. Use array concatenation to concatenate itself with another scalar:

   x = [x num]
   

2. Use the end+1 notation, to address the first available location:

   x(end+1) = num
   

Both of the above two notations also work when you want to append a row or a column vector to an existing row vector or column vectors. But when you are concatenating vectors/matrices, remember to be consistent with the dimensions.