This is a Fortran implementation of the geodesic algorithms described in

  C. F. F. Karney,
  Algorithms for geodesics,
  J. Geodesy 87, 43-55 (2013);
  https://doi.org/10.1007/s00190-012-0578-z
  Addenda: https://geographiclib.sourceforge.io/geod-addenda.html

For documentation, see

  https://geographiclib.sourceforge.io/html/Fortran/

The code in this directory is entirely self-contained.  In particular,
it does not depend on the C++ classes.  You can compile and link the
example programs directly with something like:

  f95 -o geodinverse geodinverse.for geodesic.for
  echo 30 0 29.5 179.5 | ./geodinverse

Alternatively, you can build the examples using cmake.  For example, on
Linux systems you might do:

  mkdir BUILD
  cd BUILD
  cmake ..
  make
  echo 30 0 29.5 179.5 | ./geodinverse

The two tools ngsforward and ngsinverse are replacements for the NGS
tools FORWARD and INVERSE available from

  http://www.ngs.noaa.gov/PC_PROD/Inv_Fwd/