E04 Chapter Contents
E04 Chapter Introduction
NAG Library Manual

# NAG Library Routine DocumentE04VGF

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

E04VGF is used to initialize the routine E04VHF.

## 2  Specification

 SUBROUTINE E04VGF ( CW, LENCW, IW, LENIW, RW, LENRW, IFAIL)
 INTEGER LENCW, IW(LENIW), LENIW, LENRW, IFAIL REAL (KIND=nag_wp) RW(LENRW) CHARACTER(8) CW(LENCW)

## 3  Description

E04VGF initializes the arrays CW, IW and RW for the routine E04VHF.

None.

## 5  Parameters

1:     CW(LENCW) – CHARACTER(8) arrayCommunication Array
2:     LENCW – INTEGERInput
On entry: the dimension of the array CW as declared in the (sub)program from which E04VGF is called.
Constraint: ${\mathbf{LENCW}}\ge 600$, see routine E04VHF.
3:     IW(LENIW) – INTEGER arrayCommunication Array
4:     LENIW – INTEGERInput
On entry: the dimension of the array IW as declared in the (sub)program from which E04VGF is called.
Constraint: ${\mathbf{LENIW}}\ge 600$, see routine E04VHF.
5:     RW(LENRW) – REAL (KIND=nag_wp) arrayCommunication Array
6:     LENRW – INTEGERInput
On entry: the dimension of the array RW as declared in the (sub)program from which E04VGF is called.
Constraint: ${\mathbf{LENRW}}\ge 600$, see routine E04VHF.
7:     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:
${\mathbf{IFAIL}}=1$
One or more of the communication array lengths LENCW, LENIW or LENRW is less than $600$.

## 7  Accuracy

Not applicable.

The time taken by E04VGF is negligible.

## 9  Example

See Section 9 in E04VHF and E04VKF.