Table 12-3 describes each Compaq Fortran 3f library routine and lists the appropriate reference page. For those 3f library routines that serve as interface routines to a system call or a different library routine, the required related routine is listed. Most routines are invoked as functions, with the exception of those listed as subroutines in Table 12-3.

Table 12-3 Compaq Fortran 3f Functions and Subroutines

Name	Reference Page	Description
abort	abort(3f)	Terminates the program abnormally and may cause a core dump. Use as a subroutine.
access	access(3f)	Determines the accessibility of a file.
alarm	alarm(3f)	Executes a subroutine after a specified time.
and	bit(3f)	Returns the bitwise AND of two operands. Use as an intrinsic function.
besj0	bessel(3f)	Returns single-precision (REAL*4) bessel function value (first kind, zero order).
besj1	bessel(3f)	Returns single-precision (REAL*4) bessel function value (first kind, first order).
besjn	bessel(3f)	Returns single-precision (REAL*4) bessel function value (first kind, nth order).
besy0	bessel(3f)	Returns single-precision (REAL*4) bessel function value (second kind, zero order).
besy1	bessel(3f)	Returns single-precision (REAL*4) bessel function value (second kind, first order).
besyn	bessel(3f)	Returns single-precision (REAL*4) bessel function value (second kind, nth order).
chdir	chdir(3f)	Changes the default directory.
chmod	chmod(3f)	Changes the mode of a file.
ctime	time(3f)	Returns the system time as a 24-character ASCII string.
dbesj0	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (first kind, zero order).
dbesj1	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (first kind, first order).
dbesjn	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (first kind, nth order).
dbesy0	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (second kind, zero order).
dbesy1	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (second kind, first order).
dbesyn	bessel(3f)	Returns a double-precision (REAL*8) bessel function value (second kind, nth order).
derf	erf(3f)	Returns a double-precision error function.
derfc	erf(3f)	Returns a double-precision error function (complementary form).
drand	rand(3f)	Generates a random number. Use drandm instead.
drandm	random(3f)	Generates a double-precision (REAL*8) random number.
dtime	etime(3f)	Returns the elapsed (delta) execution time.
erf	erf(3f)	Returns a single-precision error function.
erfc	erf(3f)	Returns a single-precision error function (complementary form).
etime	etime(3f)	Returns the actual execution time of a process.
falloc	malloc(3f)	Allocates space for an array in virtual memory. Use with malloc and free . Consider using the ALLOCATABLE attribute or the ALLOCATE and DEALLOCATE statements.
fdate	fdate(3f)	Returns the date and time in ASCII string. Use as a subroutine.
fgetc	fgetc(3f)	Returns a character from a specified logical unit.
flush	flush(3f)	Writes (flushes) the output in a user buffer to system buffer. Discards read-ahead data in user buffer.
for_get_fpe	for_set_fpe(3f)	Returns the status of the floating-point exception (fpe) handling currently set for the program. Usually used with for_set_fpe . To use for_set_fpe and for_get_fpe from a C program, see the for_rtl_init_ routine in this table. For more information, see Section 3.37.
for_rtl_init_	for_rtl_init_(3f)	Initializes the Compaq Fortran run-time library (RTL) environment for a C program. Use this subroutine from a main program written in C that calls Compaq Fortran subprograms. Calling this subroutine from the main C program initializes Compaq Fortran RTL data. It also establishes Compaq Fortran RTL signal handlers and floating-point exception handling so that the Compaq Fortran subprograms behave as if they were the main program. The trailing underscore (_) is required, and this routine must be called from a C program. For an example of for_rtl_init_, see Section 11.4.
for_rtl_finish_	for_rtl_init_(3f)	Cleans up the Compaq Fortran run-time library (RTL) environment for a C main program that previously called for_rtl_init_ . A status value is returned by this function. The trailing underscore (_) is required, and this routine must be called from a C program. Also see for_rtl_init_ .
for_set_fpe	for_set_fpe(3f)	Changes the floating-point exception (fpe) handling currently set for the program and also returns the status of the previous floating-point exception (fpe) handling setting. Can be used with for_get_fpe . For more information, see Section 3.37.
fork	fork(3f)	Creates a copy of the calling process.
fputc	putc(3f)	Writes a character to a specified logical unit.
free	malloc(3f)	Frees the memory allocated by falloc or malloc . Consider using the ALLOCATABLE attribute or the ALLOCATE and DEALLOCATE statements.
fseek	fseek(3f)	Repositions a file on a logical unit.
fstat	stat(3f)	Returns information about file status. The file is specified as a Fortran 95/90 logical unit number.
fsync	fsync(3f)	Writes the output in buffer to permanent storage.
ftell	fseek(3f)	Repositions a file on a logical unit.
gerror	perror(3f)	Writes system error messages.
getarg	getarg(3f)	Returns the command line arguments.
getc	getc(3f)	Returns a character from a logical unit.
getcwd	getcwd(3f)	Returns the directory path of the current directory.
getenv	getenv(3f)	Returns the value of environment variables.
getfd	getfd(3f)	For a file already opened by the Compaq Fortran Run-Time Library, returns the file descriptor associated with a particular unit number.
getgid	getuid(3f)	Returns the group's id of the caller.
getlog	getlog(3f)	Returns the user's login name.
getpid	getuid(3f)	Returns the process id.
getuid	getuid(3f)	Returns the user's or group's id of the caller.
gmtime	time(3f)	Returns the system time in month, day, and so forth in G.M.T. (Greenwich Mean Time).
iargc	getarg(3f)	Returns the command line arguments.
idate	idate(3f)	Returns the date or time in numeric form. Also available as an intrinsic subroutine (Compaq extension) described in the Compaq Fortran Language Reference Manual.
ierrno	perror(3f)	Returns a system error message number.
index	index(3f)	Returns the index of a substring within the string. Consider using INDEX intrinsic function described in the Compaq Fortran Language Reference Manual.
irand	rand(3f)	Generates random values. For an example program that uses irand , see Section 12.7.
irandm	random(3f)	Generates a positive integer random number.
isatty	ttynam(3f)	Returns whether the specified unit is a terminal port. Use as a subroutine.
itime	idate(3f)	Returns the date or time in numeric form.
kill	kill(3f)	Sends a signal to a process.
len	index(3f)	Returns the length of a string. Use the LEN intrinsic function described in the Compaq Fortran Language Reference Manual.
link	link(3f)	Makes a directory link to an existing file.
lnblnk	index(3f)	Returns the index of the last nonblank character in a string.
loc	loc(3f)	Returns the address of an object. Similar to the %LOC built-in function described in the Compaq Fortran Language Reference Manual.
long	long(3f)	Converts INTEGER*2 to INTEGER*4.
lshift	bit(3f)	Shifts a word left by n bits. Use as an intrinsic function.
lstat	stat(3f)	Returns information about a file or a symbolic link.
ltime	time(3f)	Returns the system time in month, day, hour, minute, and seconds for the time zone.
malloc	malloc(3f)	Returns the address of a block of virtual memory. See also free . Consider using the ALLOCATABLE attribute or the ALLOCATE and DEALLOCATE statements.
not	bit(3f)	Returns the bitwise NOT (complement) of the operand. Use as an intrinsic function.
omp_set_num_threads	omp_set_num_threads(3f)	(TU*X ONLY) Sets the number of threads to use for the next parallel region.
omp_get_num_threads	omp_get_num_threads(3f)	(TU*X ONLY) Gets the number of threads currently in the team executing the parallel region from which the routine is called.
omp_get_max_threads	omp_get_max_threads(3f)	(TU*X ONLY) Gets the maximum value that can be returned by calls to the omp_get_num_threads() function.
omp_get_thread_num	omp_get_thread_num(3f)	(TU*X ONLY) Gets the thread number, within the team, in the range from zero to omp_get_num_threads() minus one.
omp_get_num_procs	omp_get_num_procs(3f)	(TU*X ONLY) Gets the number of processors that are available to the program.
omp_in_parallel	omp_in_parallel(3f)	(TU*X ONLY) Informs whether or not a region is executing in parallel.
omp_set_dynamic	omp_set_dynamic(3f)	(TU*X ONLY) Enables or disables dynamic adjustment of the number of threads available for execution of parallel regions.
omp_get_dynamic	omp_get_dynamic(3f)	(TU*X ONLY) Informs if dynamic thread adjustment is enabled.
omp_set_nested	omp_set_nested(3f)	(TU*X ONLY) Enables or disables nested parallelism.
omp_get_nested	omp_get_nested(3f)	(TU*X ONLY) Informs if nested parallelism is enabled.
omp_init_lock	omp_init_lock(3f)	(TU*X ONLY) Initializes a lock to be used in subsequent calls.
omp_destroy_lock	omp_destroy_lock(3f)	(TU*X ONLY) Disassociates a lock variable from any locks.
omp_set_lock	omp_destroy_lock(3f)	(TU*X ONLY) Makes the executing thread wait until the specified lock is available.
omp_unset_lock	omp_set_lock(3f)	(TU*X ONLY) Releases the executing thread from ownership of the lock.
omp_test_lock	omp_unset_lock(3f)	(TU*X ONLY) Try to set the lock associated with a lock variable.
or	bit(3f)	Returns the bitwise OR of two operands. Use as an intrinsic function.
perror	perror(3f)	Writes system error messages.
putc	putc(3f)	Writes a character to a Fortran 95/90 logical unit.
qsort	qsort(3f)	Performs a quick sort of array elements. For an example program that uses qsort , see Section 12.7.
rand	rand(3f)	Generates random values.
random	random(3f)	Generates a single-precision (REAL) random number.
rename	rename(3f)	Renames a file.
rindex	index(3f)	Returns index of a substring within the string. See also index and the INDEX intrinsic function described in the Compaq Fortran Language Reference Manual.
rshift	bit(3f)	Shifts a word right by n bits. Use as an intrinsic function.
short	long(3f)	Converts INTEGER*4 to INTEGER*2.
shcom_connect	shcom_connect(3f)	(TU*X ONLY) Allows multiple processes to access common block data in a shared library (uses memory mapping).
signal	signal(3f)	Changes the action of a signal.
sleep	sleep(3f)	Suspends execution for an interval.
srand	rand(3f)	Initializes the seed for subsequent use of rand and irand .
stat	stat(3f)	Returns information about the status of specified file.
symlnk	link(3f)	Makes a symbolic directory link to an existing file.
system	system(3f)	Executes a shell command.
time	time(3f)	Returns the system time in number of seconds from 00:00:00 G.M.T. January 1, 1970. Also available as an intrinsic subroutine (Compaq extension) described in the Compaq Fortran Language Reference Manual.
ttynam	ttynam(3f)	Returns the name of a terminal port or returns blanks if specified unit is not a terminal port.
umask	umask(3f)	Sets the file mode creation mask (protection).
unlink	unlink(3f)	Removes a directory entry. See also link .
wait	wait(3f)	Waits for the process to terminate.
xor	bit(3f)	Returns the bitwise exclusive OR of two operands. Use as an intrinsic function.

The Compaq Fortran Language Reference Manual describes other Compaq Fortran intrinsic functions and subroutines.