In MATLAB the equality operator is ==, not =. This is clearly shown in the documentation (see link I gave). The single equals sign is only used to assign a value to a variable.
vector = [1,4,6,-9,2,7,23,-6,-8,9,10,13,4,5,-8,-12,-2,1,0,11,-8,-9,3,8,9,2];
string = 'zxcv';
if string(1)=='z' % note == not =
output = vector(2)+vector(4);
disp(output)
end
displays this:
-5
Note that for testing strings it is recommended to use strcmp or strncmp instead of array equals:
>> strncmp(string,'z',1)
rather than this:
>> string(1)=='z'
