function dC = tworxns(t, C)

% Solution to the differential equations:
% dCa/dt = -4Ca + Cb
% dCb/dt = 4(Ca - Cb)
% with the following conditions:
% Ca(0) = 100; Cb(0) = 0
% M.Subramanian 
% 20-Mar-2001

dC = zeros(2,1);  % a column vector

dC(1) = -4 * C(1) + C(2);
dC(2) = 4*(C(1) - C(2));

%execute the commands prior to using this file:
%load tworxns.mat
%[t C] = ode45('tworxns',tspan,C0);
% plot(t, C)