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NAME
     etime, dtime - return elapsed time

SYNOPSIS
     real function etime (time)
     real time(2)

     real function dtime (time)
     real time(2)

DESCRIPTION
     These functions return elapsed time.

     Time is in number  of  seconds.   The  resolution  is  to  a
     nanosecond.

     NOTE: The very first call to etime or dtime may  be  inaccu-
     rate.

     If there is an error:

     o Argument elements time(1) and time(2) are undefined

     o Function return value = -1.0

     If there is no error:

     o Argument:  user time in time(1) and system time in time(2)

     o Function return value: sum of time(1) and time(2)

     dtime returns the elapsed time since the last call to dtime.

     For dtime, the elapsed time is:

     o On the first call, elapsed time since the start of  execu-
       tion

     o On the second and subsequent calls, the elapsed time since
       the last call to dtime

     o For single processor, the time used by the CPU

     o For multiple processors, the sum of times for all the CPUs
       (not useful, use etime)
       Note:  Do not call dtime from within a parallelized loop.

     etime returns the elapsed time since the start of execution.

     For etime, the elapsed time is:

     o For single  processor:   the  CPU  time  for  the  calling
       process

     o For multiple processors:  the wall-clock time  while  run-
       ning your program
       Note:  time(1) contains the wall clock  time;  time(2)  is
       0.0.

     f77 determines single versus multiple  processing  depending
     on  whether  a program is linked with the multithreaded ver-
     sion of the  FORTRAN  77  library,  libF77_mt,  and  if  the
     environment variable PARALLEL is:

     Undefined,
          then the current run is single processor.

     Defined, and in the range 1, 2, 3, ...,
          then the current run is multiple processor.

     Defined, but some value other than 1, 2, 3, ...,
          then the results are unpredictable.

FILES
     libF77.a, libF77_mt.a, libF77.so, libF77_mt.so

SEE ALSO
     times(2), f77(1),  Fortran  User's  Guide  and  the  Fortran
     Library Reference

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