NAG FL Interface
x04abf returns the value of the current advisory message unit number, or sets the current advisory message unit number to a new value.
|Integer, Intent (In)
|Integer, Intent (Inout)
C Header Interface
x04abf_ (const Integer *iflag, Integer *nadv)
The routine may be called by the names x04abf or nagf_file_set_unit_advisory.
enables those Library routines which output advisory messages to determine the number of the output unit to which the advisory messages are to be sent; in this case x04abf
is called with
may also be called with
to set the unit number to a specified value. Otherwise a default value (stated in the Users' Note
for your implementation) is returned.
Records written to this output unit by other Library routines are at most characters long (including a line-printer carriage control character), unless those Library routines allow you to specify longer records.
Note that if the unit number is set , no messages will be output.
: the action to be taken (see nadv
need not be set.
must specify the new advisory message unit number.
is set to the current advisory message unit number.
Note that Fortran unit numbers must be positive or zero. If nadv
, output of advisory messages is totally suppressed. It is important to note that if you supply an illegal value for nadv
(such as a unit number associated with a file opened for reading instead of writing) then x04abf
cannot detect that fact, but any output sent to the unit by later calls of NAG routines may have undesirable consequences, such as program crashes.
Error Indicators and Warnings
Parallelism and Performance
is not thread safe and should not be called from a multithreaded user program. Please see Section 1
in FL Interface Multithreading for more information on thread safety.
x04abf is not threaded in any implementation.
The time taken by x04abf is negligible.
In this example x04abf
is called by your main program to make the advisory message from the routine DUMMY appear on the same unit as the rest of the output (unit
). Normally a NAG Library routine with an IFAIL argument (see Section 4.2
in the Introduction to the NAG Library FL Interface) would take the place of DUMMY.