NAG Library Routine Document

X04AAF

X04AAF enables those library routines which output error messages, to determine the number of the output unit to which the error messages are to be sent; in this case X04AAF is called with

IFLAG = 0

. X04AAF may also be called with

IFLAG = 1

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

80

characters long (including a line-printer carriage control character).

Note that if the unit number is set

< 0

, no messages will be output.

4 References

None.

5 Parameters

1: IFLAG – INTEGERInput: On entry: the action to be taken (see NERR).
Constraint: $IFLAG = 0$ or $1$ .
2: NERR – INTEGERInput/Output: On entry: if $IFLAG = 0$ , NERR need not be set.
If $IFLAG = 1$ , NERR must specify the new error message unit number.

On exit: if $IFLAG = 0$ , NERR is set to the current error message unit number.
If $IFLAG = 1$ , NERR is unchanged.

Note that Fortran unit numbers must be positive or zero. If NERR is set $< 0$ , output of error messages is totally suppressed.

6 Error Indicators and Warnings

None.

7 Accuracy

Not applicable.

8 Further Comments

The time taken by X04AAF is negligible.

9 Example

In this example X04AAF is called by your main program to make the error message from the routine DUMMY appear on the same unit as the rest of the output (unit