Please help me get the basics here..

I have to use Euler's Method to develop a plot and I've come this far:

Code:
function y = hw1_8
% Function to determine water level in tank as a function of time
%
% Inputs:   a = Cross-Sectional Surface Area
%           Q = Flow rate
%
% Outputs: Water level as a function of time

a = 1200;
q = 500;
y = 0;
t = 0;

while t <= 10
    y = y + [3*q/a*sin(t)^2 - q/a]*(.5);
    fprintf('time = %3.1f   y = %5.2f\n', t, y);
    t = t+.5;
end

end
It returns a list of the correct values that I need, but by using my method, it dumps all of the previous values of y. How can I have it store the values as an array so that I can plot t vs. y after I'm done?

Any help is greatly appreciated, I'd love to be good at Matlab!