D02NPF (PDF version)
D02 Chapter Contents
D02 Chapter Introduction
NAG Library Manual

NAG Library Routine Document

D02NPF

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.

+− Contents

    1  Purpose
    2  Specification
    3  Description
    4  References
    5  Parameters
    6  Error Indicators and Warnings
    7  Accuracy
    8  Further Comments
    9  Example

1  Purpose

D02NPF is a setup routine which you must call prior to D02NEF and after a call to D02MWF, if the Jacobian is to be considered as having a banded structure.

2  Specification

SUBROUTINE D02NPF (NEQ, ML, MU, ICOM, LICOM, IFAIL)
INTEGERNEQ, ML, MU, ICOM(LICOM), LICOM, IFAIL

3  Description

A call to D02NPF specifies that the Jacobian to be used is banded in structure. If D02NPF is not called before a call to D02NEF then the Jacobian is assumed to be full.

4  References

None.

5  Parameters

1:     NEQ – INTEGERInput
On entry: the number of differential-algebraic equations to be solved.
Constraint: 1≤NEQ.
2:     ML – INTEGERInput
On entry: mL, the number of subdiagonals in the band.
Constraint: 0≤ML≤NEQ-1.
3:     MU – INTEGERInput
On entry: mU, the number of superdiagonals in the band.
Constraint: 0≤MU≤NEQ-1.
4:     ICOM(LICOM) – INTEGER arrayCommunication Array
ICOM is used to communicate details of the integration from D02MWF and details of the banded structure of the Jacobian to D02NEF.
5:     LICOM – INTEGERInput
On entry: the dimension of the array ICOM as declared in the (sub)program from which D02NPF is called.
Constraint: LICOM≥50+NEQ.
6:     IFAIL – INTEGERInput/Output
On entry: IFAIL must be set to 0, -1​ or ​1. If you are unfamiliar with this parameter you should refer to Section 3.3 in the Essential Introduction for details.
On exit: IFAIL=0 unless the routine detects an error (see Section 6).
For environments where it might be inappropriate to halt program execution when an error is detected, the value -1​ 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 -1​ or ​1 is used it is essential to test the value of IFAIL on exit.

6  Error Indicators and Warnings

If on entry 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:
IFAIL=1
On entry,NEQ<1.
IFAIL=2
On entry,ML<0 or ML>NEQ-1.
IFAIL=3
On entry,MU<0 or MU>NEQ-1.
IFAIL=4
Either D02MWF has not been called before this call or the communication array ICOM has been corrupted.
IFAIL=5
On entry,LICOM<50+NEQ.

7  Accuracy

Not applicable.

8  Further Comments

None.

9  Example

See Section 9 in D02NEF and D02MWF.
D02NPF (PDF version)
D02 Chapter Contents
D02 Chapter Introduction
NAG Library Manual
© The Numerical Algorithms Group Ltd, Oxford, UK. 2009