The NAG Fortran Library

The world’s largest collection of robust, documented, tested and maintained numerical algorithms.
Unrivalled Reliability
Algorithms that work for your applications. Flexible to the core.

If you need to add mathematical and statistical functionality to your applications or if you have complex mathematical problems to solve, the NAG Fortran Library will provide a host of benefits. The NAG Library provides a solid numerical foundation and serves diverse mathematical areas. It is expertly documented, maintained and supported and is regularly updated with cutting edge algorithmic capabilities.

Accelerating development of your algorithm-reliant application

When Schroders were developing an in-house portfolio construction tool they massively reduced their development time by using NAG routines by creating 20 optimal portfolios in the same time that it used to take to create one. This gave them more time to focus on other value added areas. Learn more

Quick tour of the NAG Toolbox for MATLAB

Speed up time to market / application development
Deliver competitive advantage
Thread Safety
Growth strategy
Available for all these languages and environments
Product Details

The complete NAG Fortran Library Manual, Mark 26.1 can be viewed on-line in the following formats:

  • HTML: the full manual available as HTML (using HTML5 features such as MathML and SVG in suitable browsers);
  • PDF: the same manual as above, consisting of many PDF files, may be browsed via the HTML table of contents pages;
  • ZIP file: the archive as a ZIP file;

Advice on viewing and navigating the first three formats can be found in the How to Use the NAG Library and its Documentation document. You are strongly advised to read this document if you wish to try the HTML format.

The two single file formats are more compact than the formats using one file per routine, but of course are a larger download if you only need to view the documentation for a few routines.

The Library is organized into Chapters - each being documented with its own Introduction and Contents list followed by a comprehensive document for each function detailing its purpose, description, list of parameters and possible error exits. Example programs and results are also supplied. All examples are available on-line to facilitate their use as templates for the users' calling programs.

The known issues document reflects all reported and resolved issues that affect various releases of the NAG Fortran Library, along with suggested workarounds where possible.

Some Fortran Library long names have been changed, you can find a full list of the changes here.

The NAG Fortran Library Manual - prior releases

The previous marks of the NAG Fortran Library Manual are still available: Mark 26.0, Mark 25 and Mark 24.

A full list of routines withdrawn from past marks of the Library has been provided with pointers to the recommended replacement routine.

Installer's Notes and Users' Notes

Support documentation for the installation and use of each implementation of the NAG Fortran Library is available.

Technical Information

Technical information, including information on calling the NAG Fortran Library from various different environments, is available from the NAG Fortran Library Associated Information page.

Produced by experts for use in a variety of applications, the NAG Library is the largest commercially available collection of numerical and statistical algorithms in the world. With over 1,600 tried and tested routines that are both flexible and portable it remains at the core of thousands of programs and applications spanning the globe. The NAG Library is widely used and trusted because of its unrivalled quality, reliability and portability. Whether it is a single PC or a cluster of the world’s largest supercomputers, the NAG Library has the numerical capabilities to fit your model.

The NAG Fortran Library is available as a Dynamic Link Library (DLLs) for use on Windows systems.

The following table provides a simple mechanism by which you can determine the most appropriate NAG Fortran Library implementation for your needs. The table is organized by grouping implementations firstly by operating system and secondly by compiler; you simply select the combination appropriate to the system that you use. The most important information that you can derive from this is the NAG product code which is located in the rightmost column of each record and is a 10 character string beginning FL.


DLL (Windows API) 32-bit FLDLL26DEL
Intel Fortran 32-bit FLW3225DCL
Intel Fortran 32-bit FLW3226DEL
Intel Fortran 64-bit FLW6I25DCL
Intel Fortran 64-bit (ILP64) FLW6I24DDL
Intel Fortran 64-bit FLW6I26DEL

Linux (x86)

Intel Fortran 64-bit FLL6I26DCL
GNU Fortran 64-bit FLL6I26DFL
NAG Fortran 64-bit FLL6I26D9L
GNU Fortran 64-bit (ILP64) FLL6A23DHL
PGI f90 64-bit FLL6A24DPL
Intel Fortran 32-bit FLLUX26DCL
GNU Fortran 32-bit FLL3A22DFL
NAG Fortran 32-bit FLL3A23D9L

Linux (Power6)

IBM xlf 64-bit FLIL622DAL

Mac OS X

Intel Fortran 64-bit FLMI626DCL
GNU gfortran 64-bit FLMI6261FL
NAG Fortran 64-bit FLMI626D9L


IBM xlf 64-bit FLAI623DAL
IBM xlf 32-bit FLAI321DAL
NAG Fortran 32-bit FLAI321D9L

Solaris (SPARC)

Sun f95 32-bit FLSOL22DCL
Oracle Fortran 64-bit FLSO626DCL

Solaris (x86)

Sun f95 64-bit FLSA622DCL

Services and Support

Outstanding service and support from our expert team
First line technical support when you need it

NAG’s Technical Support Service is provided by a team of specialists in numerical and statistical software development, in fact the NAG Library and Compiler development team share responsibility for the support of our software. We strongly believe that in order to effectively support complex software the technicians must be both experienced and understand the intricacies of the computational techniques. This conviction is reflected in the composition of the team most of whom are qualified to PhD level and have combined experience of software support in excess of 50 years.

NAG accuracy is quality assured

NAG provides accurate, documented, numerical software and services to help you make sure that your results are accurate. The validity of each NAG routine is tested for each platform that it is enabled for. Only when an implementation satisfies our stringent accuracy standards is it released. As a result, you can rely on the proven accuracy and reliability of NAG to give you the right answers. NAG is an ISO 9001 certified organization.

Reap the benefits of NAG expertise

The numerical codes that underpin the results from your software are not future proof. While the mathematics does not change, the codes have a limited lifespan because of new hardware structures, mathematical innovation and changes in application needs. NAG Numerical Services help you and your organization find and implement the optimum numerical computation solutions. NAG works with your team to impart skills and techniques that will help solve your numerical software problems.

Expert teaching and instruction from numerical experts

Your users, developers and managers can all benefit from NAG's highly regarded training courses. All of the training courses shown below have been delivered successfully either from NAG offices or at client premises. Training courses can be tailored to suit your particular requirements and be targeted to novice, intermediate or experienced levels. Specialized mentoring and development programs are also available for HPC managers.

Working in collaboration with industry and academia

NAG was founded on collaboration as an inter-University collaborative venture combining the talents of mathematicians and computer scientists. NAG has continued to collaborate with individuals and organizations over the past four decades and today longstanding and new partners are delivering tangible benefits to users and students all over the world.