NAG Library Routine Document

e04wlf (nlp2_option_double_get)


    1  Purpose
    7  Accuracy
    10  Example


e04wlf is used to get the value of a real optional parameter. e04wlf can be used before or after calling e04wdf.


Fortran Interface
Subroutine e04wlf ( string, rvalue, iw, rw, ifail)
Integer, Intent (Inout):: iw(*), ifail
Real (Kind=nag_wp), Intent (Inout):: rw(*)
Real (Kind=nag_wp), Intent (Out):: rvalue
Character (*), Intent (In):: string
C Header Interface
#include nagmk26.h
void  e04wlf_ (const char *st, double *rvalue, Integer iw[], double rw[], Integer *ifail, const Charlen length_st)


e04wlf obtains the current value of a real option. For example
Call e04wlf ('LU Factor Tolerance', factol, iw, rw, ifail)
will result in the value of the optional parameter LU Factor Tolerance being output in FACTOL.
A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in e04wdf.




1:     string – Character(*)Input
On entry: a single valid keyword of a real optional parameter (as described in Section 12 in e04wdf).
2:     rvalue – Real (Kind=nag_wp)Output
On exit: the real value associated with the keyword in string.
3:     iw* – Integer arrayCommunication Array
Note: the dimension of the array iw must be at least leniw (see e04wcf).
4:     rw* – Real (Kind=nag_wp) arrayCommunication Array
Note: the dimension of the array rw must be at least lenrw (see e04wcf).
5:     ifail – IntegerInput/Output
On entry: ifail must be set to 0, -1​ or ​1. If you are unfamiliar with this argument you should refer to Section 3.4 in How to Use the NAG Library and its Documentation for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value -1​ or ​1 is recommended. If the output of error messages is undesirable, then the value 1 is recommended. Otherwise, if you are not familiar with this argument, the recommended value is 0. When the value -1​ or ​1 is used it is essential to test the value of ifail on exit.
On exit: ifail=0 unless the routine detects an error or a warning has been flagged (see Section 6).

Error Indicators and Warnings

If on entry ifail=0 or -1, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
The initialization routine e04wcf has not been called.
The supplied option is invalid. Check that the keywords are neither ambiguous nor misspelt.
An unexpected error has been triggered by this routine. Please contact NAG.
See Section 3.9 in How to Use the NAG Library and its Documentation for further information.
Your licence key may have expired or may not have been installed correctly.
See Section 3.8 in How to Use the NAG Library and its Documentation for further information.
Dynamic memory allocation failed.
See Section 3.7 in How to Use the NAG Library and its Documentation for further information.


Not applicable.

Parallelism and Performance

e04wlf is not threaded in any implementation.

Further Comments



See Section 10 in e04wef.
© The Numerical Algorithms Group Ltd, Oxford, UK. 2017