e04vnf may be used to supply individual real optional parameters to e04vhf. The initialization routine e04vgf must have been called before calling e04vnf.

2 Specification

Fortran Interface

Subroutine e04vnf (

string, rvalue, cw, 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
Character (8), Intent (InOut)	::	cw(*)

C Header Interface

#include <nag.h>

void	e04vnf_ (const char st, const double rvalue, char cw[], Integer iw[], double rw[], Integer *ifail, const Charlen length_st, const Charlen length_cw)

The routine may be called by the names e04vnf or nagf_opt_nlp2_sparse_option_double_set.

3 Description

e04vnf may be used to supply values for real optional parameters to e04vhf. It is only necessary to call e04vnf for those arguments whose values are to be different from their default values. One call to e04vnf 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 e04vnf ('LU Factor Tolerance', factol, cw, iw, rw, ifail)

Optional parameter settings are preserved following a call to e04vhf 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 e04vhf.

A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in e04vhf.

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 e04vhf).
2: $rvalue$ – Real (Kind=nag_wp) Input: On entry: the value associated with the keyword in string.
3: $cw (*)$ – Character(8) array Communication Array: Note: the actual argument supplied must be the array cw supplied to the initialization routine e04vgf.
4: $iw (*)$ – Integer array Communication Array: Note: the actual argument supplied must be the array iw supplied to the initialization routine e04vgf.
5: $rw (*)$ – Real (Kind=nag_wp) array Communication Array: Note: the actual argument supplied must be the array rw supplied to the initialization routine e04vgf.
6: $ifail$ – 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 e04vgf 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.