gencodata generates physical constant header files in C, Fortran, and Python syntaxes.

gencodata's physical constant values are current and authoritative since they are extracted from the NIST CODATA 2014 document SRD121 , a machine-parsable summary of the primary reference:

CODATA recommended values of the fundamental physical constants: 2014
Peter J. Mohr, David B. Newell,and Barry N. Taylor
REVIEWS OF MODERN PHYSICS, VOLUME 88, JULY-SEPTEMBER 2016 (73 pages)
DOI: 10.1103/RevModPhys.88.035009

The reference article is linked from NIST Reference on Constants,Units,and Uncertainty

gencodata universal --syntax fortran --output universal.Fh

The short form is:

gencodata universal -s f -o universal.Fh

Without arguments, the gencodata command prints:

gencodata generates CODATA physical constants
header files in C, Fortan, or Python(default) syntax.

usage: gencodata [-h] [-l] [-i INPUT] [-o OUTPUT] [-c CSV] [-j JSON]
            [-s SYNTAX]
            [category [category ...]]

For more information, type:

gencodata --help

Copyright 2017, Daniel R. Haney