In Chaps. 77 and 79 , linear (ordinary) differential equations or initial value problems with linear (ordinary) differential equations were solved using Fourier- and Laplace transformations. Here, we took advantage of the fact that the transformation turns a differential equation into an algebraic equation. This equation is then usually easy to solve, and the inverse transform is then a solution to the original differential equation. This principle can also be successfully applied to partial differential equations: From a partial differential equation, an ordinary differential equation is obtained by integral transformation. This is then solved using conventional methods, a reverse transformation then provides a solution to the original partial differential equation. In general, one obtains solution formulas for the considered partial differential equation with possibly given initial conditions.