The Fortran 90 Handbook is a definitive and comprehensive guide to Fortran 90 and its use. Fortran 90, the latest standard version of Fortran, has many excellent new features that will assist the programmer in writing efficient, portable, and maintainable programs. The Fortran 90 Handbook is an informal description of Fortran 90, developed to provide not only a readable explanation of features, but also some rationale for the inclusion of features and their use. In addition, “models” give the reader better insight as to why things are done as they are in the language.