clear all; close all;
% Grid:
N = 2^8; L = 10;
x2 = linspace(-L/2,L/2,N+1);
x = x2(1:N);
k = 2*pi/L*[0:N/2-1 -N/2:-1];
% Diffusion parameter:
kappa = .5;
% Time span for solution:
tspan = [0:1:10];
% Create initial condition:
U0 = exp(-x.^2);
Ut0 = fft(U0);
% Call ODE solver:
[t,Ut] = ode45('specrhs',tspan,Ut0,[],k,kappa);
for j = 1:length(t)
 U(j,:) = ifft(Ut(j,:));
end