         NAME
              isopen - Determines whether output file is open

         SYNOPSIS
              #include "lpj.h"

              Bool isopen(const Outputfile *output,int index);

         DESCRIPTION
              Function determines whether output data file has been
              successfully opened.  The arguments of isopen are:

              output
                   Pointer to initialized output data. output must be
                   initialized by fopenoutput().

              index
                   Index of output data file to be checked.

         RETURN VALUE
              Function returns TRUE if output for index has been opened,
              FALSE otherwise.

         AUTHORS
              Werner von Bloh (Werner.von.Bloh@pik-potsdam.de), Sibyll
              Schaphoff (Sibyll.Schaphoff@pik-potsdam.de), Stefanie Rost
              (Jachner) (Stefanie.Rost@pik-potsdam.de), Marlies
              Gumpenberger (Marlies.Gumpenberger@pik-potsdam.de), Tim
              Beringer (Erbrecht) (Tim.Beringer@pik-potsdam.de), Christoph
              Mueller (Christoph.Mueller@pik-potsdam.de) Jens Heinke
              (Jens.Heinke@pik-potsdam.de), Hester Biemans
              (Hester.Biemans@wur.nl), Kirsten Thonicke
              (Kirsten.Thonicke@pik-potsdam.de), Ursula Heyder
              (Ursula.Heyder@pik-potsdam.de),

         SEE ALSO
              fopenoutput(3), fcloseoutput(3)