Heat kernel (source code)

= Heat kernel
{wiki}

For $u_t=\kappa u_{xx}$ on the real line,
$$
K_t(x)=\frac1{\sqrt{4\pi\kappa t}}e^{-x^2/(4\kappa t)}
$$
has total mass one and converges to the delta distribution as $t$ decreases to zero. The solution is $u(t)=K_t*u_0$.