function [ft] = fheat(N,t)
% Fourier Expansion of abs(x) on (0,2*pi)
% Output:  function ft = Nth partial sum of Fourier Series
% Input:  N = Number of terms to take in summation


K = 0.1;
% Define interval of interest:
x = [0:0.005:pi];

% Zero output function:
ft = zeros(1,length(x));

%Set a0 term:
ft = 0;

% Compute each 'a' and 'b' and sum:
for n = 1:N
   a = 0;
   b = 20*(1-(-1)^n)/(n*pi);
   b = 40/((2*n-1)*pi);
   b = b*exp(-K*(2*n-1)^2*t);
   ft = ft + a*cos(n*x) + b*sin((2*n-1)*x);
end

% All Done!
return