C Header Interface

#include <nag.h>

void	e04wlf_ (const char st, double rvalue, Integer iw[], double rw[], Integer *ifail, const Charlen length_st)

The routine may be called by the names e04wlf or nagf_opt_nlp2_option_double_get.

3 Description

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.

4 References

None.

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 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).

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:

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

$ifail = - 99$: 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.