$\renewcommand{\Re}{\operatorname{Re}}$ $\renewcommand{\Im}{\operatorname{Im}}$ $\newcommand{\erf}{\operatorname{erf}}$ $\newcommand{\dag}{\dagger}$

$\newcommand{\const}{\mathrm{const}}$

What one needs to know?

1. Multivariable Calculus
2. Ordinary Differential Equations
3. Partial Differential Equations
4. Complex Variables

Assets: (useful but not required)

1. Elements of (Real) Analysis,
2. Any courses in Physics, Chemistry etc using PDEs (taken previously or now).

$\Leftarrow$  $\Uparrow$  $\Rightarrow$