Desiderata

This is a list of improvements that I'm planning. Help me prioritize these items.

• Write the preface.

• In section 3.1, show how to plot implicitly-defined functions using SageMath using the plot_implicit() command.

• In section 5.2, draw the trigonometric triangle that should accompany most examples. Do the same in section 7.1.

• Add support for the SageMath show() command that displays functions more nicely than the print command, e.g. G(s) = 1 / ((s - 1) * (s + 2) * (s + 4)) followed by G.show().