Your code will work with one simple change:
function[x,y] = readCoordinates(n)
x = zeros(n,1);
y = zeros(n,1);
for i = 1:n
enterString = input('Please enter coordinates within parentheses seperated by a comma.','s');
components = sscanf(enterString,'%c%f%c%f%c');
x(i) = components(2);
y(i) = components(4);
This will search for floating point numbers which will solve the problem.
You might also consider changing,
'%c%f%c%f%c' to '(%f,%f)'
which would require changing,
x(i) = components(1);
y(i) = components(2);
but this is more of a stylistic preference, and I haven't fully considered the repercussions of either.
Hope this helps!