E05 Chapter Contents
E05 Chapter Introduction
NAG Library Manual

NAG Library Routine DocumentE05JGF

Note:  before using this routine, please read the Users' Note for your implementation to check the interpretation of bold italicised terms and other implementation-dependent details.

1  Purpose

E05JGF may be used to supply individual real optional parameters to E05JBF. The initialization routine E05JAF must have been called before calling E05JGF.

2  Specification

 SUBROUTINE E05JGF ( OPTSTR, RVALUE, COMM, LCOMM, IFAIL)
 INTEGER LCOMM, IFAIL REAL (KIND=nag_wp) RVALUE, COMM(LCOMM) CHARACTER(*) OPTSTR

3  Description

E05JGF may be used to supply values for real optional parameters to E05JBF. It is only necessary to call E05JGF for those parameters whose values are to be different from their default values. One call to E05JGF sets one parameter value.
Each real optional parameter is defined by a single character string in OPTSTR and the corresponding value in RVALUE. For example the following illustrates how the local searches tolerance could be defined:
```LOCTOL = 1.0E-10
CALL E05JGF ('Local Searches Tolerance', LOCTOL, COMM, LCOMM, IFAIL)
```
A complete list of optional parameters, their symbolic names and default values is given in Section 11 in E05JBF.

None.

5  Parameters

1:     OPTSTR – CHARACTER(*)Input
On entry: a string identifying a real-valued optional parameter (as described in Section 11 in E05JBF).
2:     RVALUE – REAL (KIND=nag_wp)Input
On entry: the value associated with the optional parameter in OPTSTR.
3:     COMM(LCOMM) – REAL (KIND=nag_wp) arrayCommunication Array
On exit: COMM must not be altered between calls to any of the routines E05JBF, E05JCF, E05JDF, E05JEF, E05JFF, E05JGF, E05JHF, E05JJF, E05JKF and E05JLF.
4:     LCOMM – INTEGERInput
On entry: the dimension of the array COMM as declared in the (sub)program from which E05JGF is called.
Constraint: ${\mathbf{LCOMM}}\ge 100$.
5:     IFAIL – INTEGERInput/Output
On entry: IFAIL must be set to $0$, $-1\text{​ or ​}1$. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction for details.
For environments where it might be inappropriate to halt program execution when an error is detected, the value $-1\text{​ or ​}1$ is recommended. If the output of error messages is undesirable, then the value $1$ is recommended. Otherwise, if you are not familiar with this parameter, the recommended value is $0$. When the value $-\mathbf{1}\text{​ or ​}\mathbf{1}$ 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).

6  Error Indicators and Warnings

If on entry ${\mathbf{IFAIL}}={\mathbf{0}}$ or $-{\mathbf{1}}$, explanatory error messages are output on the current error message unit (as defined by X04AAF).
Errors or warnings detected by the routine:
${\mathbf{IFAIL}}=1$
 On entry, ${\mathbf{LCOMM}}<100$, or the initialization routine E05JAF has not been called.
${\mathbf{IFAIL}}=2$
The optional parameter given in OPTSTR is invalid. A keyword or keyword combination was not recognized.
${\mathbf{IFAIL}}=3$
The option value to be set is out of range with respect to the optional parameter given in OPTSTR. See Section 11 in E05JBF for allowable values of the optional parameters.

Not applicable.