I am trying to add an element to the end of a matrix and i dont know the length of the matrix.
EvantCal = 999*ones(1,2); . . . . %// in a different function EventCal(end + 1) = [1, 3]; %// the numbers are random . . . this is the error I get when I run the code:
In an assignment A(I) = B, the number of elements in B and I must be the same.
The error is becasue you a trying to stuff a 1-by-2 matrix (i.e. [1, 3], which is also the B from the error message) into a single element of EventCal (note that the I in the error message is your end+1 which is a single element). Rather try
EventCal(end+1,:) = [1, 3] Here the : refers to all the columns which in your case is 2. Hence 1 row (end+1 is a single number) and 2 columns thus exactly matching the dimensions of your 2-by*1* matrix you are trying to append.
Also, if performance isn't a major issue, you can also use matrix concatenation (but this is less efficient than the indexing approach):
EventCal = [EventCal; [1,3]] 
EvantCal (end+1,:) = [1, 3];