NWTC Subroutine Library v2

A library of general-use Fortran 2003 routines used in many NWTC computer-aided engineering tools

by Marshall Buhl and Bonnie Jonkman
National Wind Technology Center

The NWTC Library has recently undergone many changes to conform to the design requirements of the FAST Modularization Framework. If you have legacy codes that have not been updated to use the newest version of the library, you can download legacy versions here.

Over the years, the staff at the NWTC have written many general-purpose routines that we use in many of our codes. In the past, we would copy those needed for any given program from the source of another code. We decided that doing it that way was just too much work—especially when we wanted to change one of the routines and have it affect all the codes. So, we decided to create a central set of routines and include their source files in our Fortran projects. Thus, the NWTC Subroutine Library was born.

The NWTC Subroutine Library consists of several modules, each contained in its own source file. The library is written in standard Fortran 2003, with the exception of some of the routines and data in the Sys*.f90 files. We currently have several compiler-specific files available to choose from, including SysIVF.f90 for the Intel Visual Fortran compiler for Windows and SysGnuLinux.f90 for the GNU Fortran compiler for Linux. If you want to port our programs to a different compiler, you should only have to modify one of the Sys*.f90 files to get it to compile. This should require only minutes (or hours at the most).

 If you have written other general-use routines and would like us to include them in our library, please email them and we will consider adding them to the library. We also welcome suggestions for desirable routines.

You may download the following files:

NWTC Subroutine Library Documentation

  • Content available in the NWTC Subroutine Library
    This is a link to the online documentation browser for NWTC Subroutine Library source code.

  • Change Log (23-Jul-2016)
    This is a list of changes made to the code. Look at this text file to see if we've made worthwhile changes since you received your previous version of the NWTC Subroutine Library.
  • NWTC Programmer's Handbook (July 2013)
    This guide for programmers contains some instructions and tips for using the NWTC Subroutine Library.

NWTC Subroutine Library Archives

  • v2.09.00, 23-Jul-2016
    The archives at the above link contain the change log, source code, and some documentation.

If you need legacy versions of NWTC Subroutine Library, you may download them here.

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If you want to refer to this website in a report, here is a reference you can use:
NWTC Information Portal (NWTC Subroutine Library v2).  https://nwtc.nrel.gov/NWTC_Library. Last modified 23-July-2016 ; Accessed 16-July-2019