Heat-kernel solution (source code)

= Heat-kernel solution

For initial data $u_0$ on the real line, Fourier transformation or convolution with the fundamental solution gives
$$
u(x,t)=\int_{-\infty}^{\infty}
\frac{e^{-(x-\xi)^2/(4Dt)}}{\sqrt{4\pi Dt}}
u_0(\xi)\,d\xi.
$$