function z=invest(x,r)
% Example loop program to debug from Palm Chapter 4.
% This program is designed to calculate the value of a series 
% of annual investments
% inputs:  x = a vector of annual investment values (dollars)
%          r = annual interest rate (%)
% output:  z = balance at the time of the last investment (dollars)


z=0;
y=1 + 0.01*r;
for k=1:length(y)
    z=z*y+x(k);
end