NAG Library Routine Document

H02CFF

H02CFF may be used to supply values for optional parameters to H02CEF. H02CFF reads an external file and each line of the file defines a single optional parameter. It is only necessary to supply values for those parameters whose values are to be different from their default values.

Each optional parameter is defined by a single character string of up to

72

characters, consisting of one or more items. The items associated with a given option must be separated by spaces, or equal signs

[=]

. Alphabetic characters may be upper or lower case. The string

 Print level = 1

is an example of a string used to set an optional parameter. For each option the string contains one or more of the following items:

–	a mandatory keyword;
–	a phrase that qualifies the keyword;
–	a number that specifies an integer or real value. Such numbers may be up to $16$ contiguous characters in Fortran 77's I, F, E or D formats, terminated by a space if this is not the last item on the line.

Blank strings and comments are ignored. A comment begins with an asterisk (*) and all subsequent characters in the string are regarded as part of the comment.

The file containing the options must start with Begin and must finish with End. An example of a valid options file is:

Begin * Example options file
Print Level = 1
End

Normally each line of the file is printed as it is read, on the current advisory message unit (see X04ABF), but printing may be suppressed using the keyword Nolist. To suppress printing of Begin, Nolist must be the first option supplied as in the file:

Begin
Nolist
Print Level = 1
End

Printing will automatically be turned on again after a call to H02CEF and may be turned on again at any time using the keyword List.

Optional parameter settings are preserved following a call to H02CEF, and so the keyword Defaults is provided to allow you to reset all the optional parameters to their default values prior to a subsequent call to H02CEF.

A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 11 in H02CEF.

4 References

None.

5 Parameters

1: IOPTNS – INTEGERInput

On entry: the unit number of the options file to be read.

Constraint:

0 \leq IOPTNS \leq 99

2: INFORM – INTEGEROutput

On exit: contains zero if the options file has been successfully read and a value

> 0

otherwise, as indicated below.

$INFORM = 1$: IOPTNS is not in the range $[0, 99]$ .
$INFORM = 2$: Begin was found, but end-of-file was found before End was found.
$INFORM = 3$: end-of-file was found before Begin was found.

6 Error Indicators and Warnings

If a line is not recognized as a valid option, then a warning message is output on the current advisory message unit (see X04ABF).

7 Accuracy

Not applicable.

8 Further Comments

H02CGF may also be used to supply optional parameters to H02CEF. Note that if E04NKF/E04NKA is used in the same program as H02CEF, then in general H02CFF will also affect the options used by E04NKF/E04NKA.

9 Example

This example solves the same problem as the example for H02CEF, but in addition illustrates the use of H02CFF and H02CGF to set optional parameters for H02CEF.

In this example the options file read by H02CFF is appended to the data file for the program (see Section 9.2). It would usually be more convenient in practice to keep the data file and the options file separate.

NAG Library Routine DocumentH02CFF

+− Contents

1 Purpose

2 Specification

3 Description