NAG Library Routine Document
To supply optional parameters to E04UCF/E04UCA
from an external file. More precisely, E04UDF must be used to supply optional parameters to E04UCF
and E04UDA must be used to supply optional parameters to E04UCA
E04UDA is a version of E04UDF that has additional parameters in order to make it safe for use in multithreaded applications (see Section 5
). The initialization routine E04WBF must
have been called before calling E04UDA.
E04UDF/E04UDA can also be used to supply optional parameters to E04UFF/E04UFA
2.1 Specification for E04UDF
2.2 Specification for E04UDA
||IOPTNS, IWSAV(610), INFORM
E04UDF/E04UDA may be used to supply values for optional parameters to
E04UDF/E04UDA 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
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 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
For E04UDF 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
must be the first option supplied as in the file:
Print level = 5
Printing will automatically be turned on again after a call to E04UCF
or E04UDF and may be turned on again at any time using the keyword List
For E04UDA 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
and so the keyword
is provided to allow you to reset all the optional parameters to their default values before a subsequent call to
A complete list of optional parameters, their abbreviations, synonyms and default values is given in
- 1: IOPTNS – INTEGERInput
On entry: the unit number of the options file to be read.
- 2: INFORM – INTEGEROutput
Note: for E04UDA, INFORM does not occur in this position in the parameter list. See the additional parameters described below
: contains zero if the options file has been successfully read and a
otherwise (see Section 6
- Note: the following are additional parameters for specific use with E04UDA. Users of E04UDF therefore need not read the remainder of this description.
- 2: LWSAV() – LOGICAL arrayCommunication Array
- 3: IWSAV() – INTEGER arrayCommunication Array
- 4: RWSAV() – REAL (KIND=nag_wp) arrayCommunication Array
The arrays LWSAV
and RWSAV must not
be altered between calls to any of the routines E04UDA, E04UCA
- 5: INFORM – INTEGEROutput
see the parameter description for INFORM
6 Error Indicators and Warnings
Errors or warnings detected by the routine:
is not in the range
Begin was found, but end-of-file was found before End was found.
end-of-file was found before Begin was found.
One or more lines of the options file is invalid. Check that all keywords are neither ambiguous nor misspelt.
may also be used to supply optional parameters to
This example solves the same problem as the example for
but in addition illustrates the use of E04UDF/E04UDA and E04UEF/E04UEA
to set optional parameters for
In this example the options file read by E04UDF/E04UDA 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.
9.1 Program Text
Note: the following programs illustrate the use of E04UDF and E04UDA.
Program Text (e04udfe.f90)
Program Text (e04udae.f90)
9.2 Program Data
Program Data (e04udfe.d)
Program Data (e04udae.d)
Program Options (e04udfe.opt)
Program Data (e04udae.opt)
9.3 Program Results
Program Results (e04udfe.r)
Program Results (e04udae.r)