How to output the calculated result into the file?

1. Issue an OPEN statement, selecting a default name.
2. Write stuff into the file, then issue a CLOSE of it.
3. Do an internal write to a string variable, to create a string like: RENAME default_file_id final_fault_id
where default_file_id is what you called it when you opened it and final_fault_id is what your program finally decides it ought to be called.
4. Issue a CALL SYSTEM(string) to do the rename.
5. Loop back to step 1 for the next file.

This presumes you are using an OS and Fortran system that let you execute system commands from Fortran and do the rename this way. All of Lahey's Fortran systems for Windows have let you do this, and most or all others as well. There would be some system-dependent issues, I imagine. You didn't specify either OS or Fortran system, so we can't give you anything more than generic answers.

You can
generate a file name (e.g. datxxx.dat where xxx is a 3 digit #)
open
write
close
increment xxx


<nbucska@pcperipherals.com>