To supply optional parameters to e04nkf/e04nka from an external file. More precisely, e04nlf must be used to supply optional parameters to e04nkf and e04nla must be used to supply optional parameters to e04nka.

e04nla is a version of e04nlf that has additional arguments in order to make it safe for use in multithreaded applications (see Section 5). The initialization routine e04wbf must have been called before calling e04nla.

2 Specification

2.1 Specification for e04nlf

Fortran Interface

Subroutine e04nlf (

ioptns, inform)

Integer, Intent (In)	::	ioptns
Integer, Intent (Out)	::	inform

C Header Interface

#include <nag.h>

void	e04nlf_ (const Integer ioptns, Integer inform)

2.2 Specification for e04nla

Fortran Interface

Subroutine e04nla (

ioptns, lwsav, iwsav, rwsav, inform)

Integer, Intent (In)	::	ioptns
Integer, Intent (Inout)	::	iwsav(380)
Integer, Intent (Out)	::	inform
Real (Kind=nag_wp), Intent (Inout)	::	rwsav(285)
Logical, Intent (Inout)	::	lwsav(20)

C Header Interface

#include <nag.h>

void	e04nla_ (const Integer ioptns, logical lwsav[], Integer iwsav[], double rwsav[], Integer inform)

3 Description

e04nlf/e04nla may be used to supply values for optional parameters to e04nkf/e04nka. e04nlf/e04nla reads an external file and each line of the file defines a single optional parameter. It is only necessary to supply values for those arguments 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 equals 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 $40$ contiguous characters in Fortran'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 = 5 
End

For e04nlf each line of the file is normally 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 = 5 
End

Printing will automatically be turned on again after a call to e04nkf or e04nlf and may be turned on again at any time using the keyword List.

For e04nla printing is turned off by default, but may be turned on at any time using the keyword List.

Optional parameter settings are preserved following a call to e04nkf/e04nka and so the keyword Defaults is provided to allow you to reset all the optional parameters to their default values before a subsequent call to e04nkf/e04nka.

A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in e04nkf/e04nka.

4 References

None.

5 Arguments

1: $ioptns$ – Integer Input: On entry: the unit number of the options file to be read.

Constraint: $0 \leq ioptns \leq 99$ .
2: $inform$ – Integer Output: Note: for e04nla, inform does not occur in this position in the argument list. See the additional arguments described below.

On exit: contains zero if the options file has been successfully read and a $value > 0$ otherwise (see Section 6).; Note: the following are additional arguments for specific use with e04nla. Users of e04nlf therefore need not read the remainder of this description.
2: $lwsav (20)$ – Logical array Communication Array
3: $iwsav (380)$ – Integer array Communication Array
4: $rwsav (285)$ – Real (Kind=nag_wp) array Communication Array: The arrays lwsav, iwsav and rwsav must not be altered between calls to any of the routines e04nla, e04nka, e04nma or e04wbf.
5: $inform$ – Integer Output: Note: see the argument description for inform above.

6 Error Indicators and Warnings

$inform = 1$: 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.

$inform = 5$: One or more lines of the options file is invalid. Check that the keywords are neither ambiguous nor misspelt.

7 Accuracy

Not applicable.

8 Parallelism and Performance

e04nlf/e04nla is not threaded in any implementation.

9 Further Comments

e04nmf/e04nma may also be used to supply optional parameters to e04nkf/e04nka.

10 Example

This example solves the same problem as the example for e04nkf/e04nka, but in addition illustrates the use of e04nlf/e04nla and e04nmf/e04nma to set optional parameters for e04nkf/e04nka.

In this example the options file read by e04nlf/e04nla is appended to the data file for the program (see Section 10.2). It would usually be more convenient in practice to keep the data file and the options file separate.