The NAG fl90 Library, Release 4, provides over 254 user-callable procedures, giving easy access to complex and highly sophisticated algorithms. Today these and very many more methods are available in the recently updated version of the The NAG Fortran Library.
The NAG fl90 includes user-callable procedures in the areas of optimization, PDEs, sparse linear algebra, linear algebra, time series and approximation.
As one would expect from NAG, the NAG fl90 is subjected to rigorous QA testing and only when it satisfies NAG's stringent accuracy standards is it released. As a result, Fortran programmers can rely on the proven accuracy, robustness and reliability of these algorithms to give them the right answers, consistently.