This book compiles the most widely applicable methods for solving and approximating differential equations, as well as numerous examples showing the methods used. Topics include ordinary differential equations, symplectic integration of differential equations, and the use of wavelets when numerically solving differential equations. For nearly every technique, the book provides: the types of equations to which the method is applicable; the idea behind the method; the procedure for carrying out the method; at least one simple example of the method; any cautions that should be exercised; notes for more advanced users; and references to the literature for more discussion or more examples, including pointers to electronic resources, such as URLs.