Many of the test problems in the web sites TestSet for IVP Solvers and Testset for BVP Solvers and , the problem descriptions and the theory of solving differential equations are contained in the new book Solving Differential Equations in R, Springer, 2012, by Karline Soetaert, Jeff Cash and Francesca Mazzia. The user is recommended to consult this reference which can be found at http://www.amazon.co.uk. R is an open source programming language and software environment for statistical computing and graphics development. The R language is widely used and highly regarded by statisticians who use it to to develop statistical software. An aim of this book is to show that R also has some important advantages as an environment when solving differential equations and this indicates that R is perhaps a more powerful language than was first appreciated.