e04whf may be used to supply individual real optional parameters to e04wdf. The initialization routine e04wcf must have been called before calling e04whf.

2 Specification

Fortran Interface

Subroutine e04whf (

string, rvalue, iw, rw, ifail)

Integer, Intent (Inout)	::	iw(*), ifail
Real (Kind=nag_wp), Intent (In)	::	rvalue
Real (Kind=nag_wp), Intent (Inout)	::	rw(*)
Character (*), Intent (In)	::	string

C Header Interface

#include <nag.h>

void	e04whf_ (const char st, const double rvalue, Integer iw[], double rw[], Integer *ifail, const Charlen length_st)

The routine may be called by the names e04whf or nagf_opt_nlp2_option_double_set.

3 Description

e04whf may be used to supply values for real optional parameters to e04wdf. It is only necessary to call e04whf for those arguments whose values are to be different from their default values. One call to e04whf sets one argument value.

Each real optional parameter is defined by a single character string in string and the corresponding value in rvalue. For example the following illustrates how the

L U

stability tolerance could be defined:

factol = 100.0E0
If (illcon) factol = 5.0E0
Call e04whf ('LU Factor Tolerance', factol, iw, rw, ifail)

Optional parameter settings are preserved following a call to e04wdf 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 e04wdf.

A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in e04wdf.

4 References

None.

5 Arguments

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) Input: On entry: the value associated with the keyword in string.
3: $iw (*)$ – Integer array Communication Array: Note: the actual argument supplied must be the array iw supplied to the initialization routine e04wcf.
4: $rw (*)$ – Real (Kind=nag_wp) array Communication Array: Note: the actual argument supplied must be the array rw supplied to the initialization routine e04wcf.
5: $ifail$ – Integer Input/Output: On entry: ifail must be set to $0$ , $−1$ or $1$ to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of $0$ causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of $−1$ means that an error message is printed while a value of $1$ means that it is not.

If halting is not appropriate, the value $−1$ or $1$ is recommended. If message printing is undesirable, then the value $1$ is recommended. Otherwise, the value $0$ is recommended. 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).

6 Error Indicators and Warnings

If on entry

ifail = 0

−1

, explanatory error messages are output on the current error message unit (as defined by x04aaf).

Errors or warnings detected by the routine:

$ifail = 1$: The initialization routine e04wcf has not been called.

$ifail = 2$: The supplied option is invalid. Check that the keywords are neither ambiguous nor misspelt. The option string is ‘ $⟨ value ⟩$ ’ and $rvalue = ⟨ value ⟩$ .

$ifail = - 99$: An unexpected error has been triggered by this routine. Please contact NAG.
See Section 7 in the Introduction to the NAG Library FL Interface for further information.

$ifail = - 399$: Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library FL Interface for further information.