function exercise10task3(theta,mu)

T = 0.2;

Nx = 21;
x = linspace(0,1,Nx);
dx = 1/(Nx-1);

dt = mu*dx^2;
t = 0:dt:floor(T/dt)*dt;

U = sin(2*pi*x)';
U = U(1:end-1);

A = -2*diag(ones(1,Nx-1)) + diag(ones(1,Nx-2),1) + diag(ones(1,Nx-2),-1);
A(1,end) = 1;
A(end,1) = 1;

A1 = eye(Nx-1) + mu * theta * A;
A2 = eye(Nx-1) - mu * (1-theta)* A;

for k = 1:length(t)-1
    U(:,k+1) = A2\(A1*U(:,k));
end

U(Nx,:) = U(1,:);

[T,X] = meshgrid(t,x);

surf(x,t,U');