At one time or another, you'll probably need to design an analog filter. Despite an abundance of digital filter design tools (for example, the excellent FDATool bundled with Matlab's Signals toolbox), ...

Despite an abundance of graphical-user-interface-based digital-filter-design tools, such as The MathWorks (www.mathworks.com) Matlab Signals toolbox, which includes the FDATool filter-analysis package ...