function y=f(x,t)

L = 1000; t0=0.1; x0 = 0.5;
c = 1; eps = 1; lambda = 1;
y = exp(-L*(t+t0)*(x-x0).^2).*(c-L*(x-x0).^2+eps*(2*L*(t+t0)-4*L^2*(t+t0)^2*(x-x0).^2)-lambda*2*L*(t+t0)*(x-x0));