# NAG FL Interfacee04nyf (qpconvex2_​sparse_​option_​double_​get)

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## 1Purpose

e04nyf is used to get the value of a real optional parameter. e04nyf can be used before or after calling e04nqf.

## 2Specification

Fortran Interface
 Subroutine e04nyf ( cw, iw, rw,
 Integer, Intent (Inout) :: iw(*), ifail Real (Kind=nag_wp), Intent (Inout) :: rw(*) Real (Kind=nag_wp), Intent (Out) :: rvalue Character (*), Intent (In) :: string Character (8), Intent (InOut) :: cw(*)
#include <nag.h>
 void e04nyf_ (const char *st, 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 e04nyf or nagf_opt_qpconvex2_sparse_option_double_get.

## 3Description

e04nyf obtains the current value of a real option. For example
`Call e04nyf ('Feasibility Tolerance', featol, cw, iw, rw, ifail)`
will result in the value of the optional parameter Feasibility Tolerance being output in FEATOL.
A complete list of optional parameters, their abbreviations, synonyms and default values is given in Section 12 in e04nqf.

None.

## 5Arguments

1: $\mathbf{string}$Character(*) Input
On entry: a single valid keyword of a real optional parameter (as described in Section 12 in e04nqf).
2: $\mathbf{rvalue}$Real (Kind=nag_wp) Output
On exit: the real value associated with the keyword in string.
3: $\mathbf{cw}\left(*\right)$Character(8) array Communication Array
Note: the actual argument supplied must be the array cw supplied to the initialization routine e04npf.
4: $\mathbf{iw}\left(*\right)$Integer array Communication Array
Note: the actual argument supplied must be the array iw supplied to the initialization routine e04npf.
5: $\mathbf{rw}\left(*\right)$Real (Kind=nag_wp) array Communication Array
Note: the actual argument supplied must be the array rw supplied to the initialization routine e04npf.
6: $\mathbf{ifail}$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 $-\mathbf{1}$ or $\mathbf{1}$ is used it is essential to test the value of ifail on exit.
On exit: ${\mathbf{ifail}}={\mathbf{0}}$ unless the routine detects an error or a warning has been flagged (see Section 6).

## 6Error Indicators and Warnings

If on entry ${\mathbf{ifail}}=0$ or $-1$, explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
${\mathbf{ifail}}=1$
The initialization routine e04npf has not been called.
${\mathbf{ifail}}=2$
The supplied option is invalid. Check that the keywords are neither ambiguous nor misspelt. The option string is ‘$⟨\mathit{\text{value}}⟩$’.
${\mathbf{ifail}}=-99$
See Section 7 in the Introduction to the NAG Library FL Interface for further information.
${\mathbf{ifail}}=-399$
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.
${\mathbf{ifail}}=-999$
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.

Not applicable.