function testode
y0 = 1;
[T Y] = ode45(@frhs, [0 2], y0);
y = ftrue(T);
subplot(311);
plot(T, Y);
title('Approximate Solution');
subplot(312);
plot(T, y);
title('True Solution');
subplot(313);
plot(T, abs(Y - y));
title('Approximation Error');
% subfunctions

function f=frhs(t, y)
f = t - y;

function f=ftrue(t)
f = 2*exp(-t)+t-1;
