NAG Library Routine Document

d02nrf (ivp_stiff_sparjac_enq)

1
Purpose

d02nrf is an enquiry routine for communicating with d02nmf or d02nnf when supplying columns of a sparse Jacobian matrix.

2
Specification

Fortran Interface
Subroutine d02nrf ( j, iplace, inform)
Integer, Intent (In):: inform(23)
Integer, Intent (Out):: j, iplace
C Header Interface
#include <nagmk26.h>
void  d02nrf_ (Integer *j, Integer *iplace, const Integer inform[])

3
Description

d02nrf is required when d02nmf or d02nnf is being used with sparse matrix linear algebra. After an exit from d02nmf or d02nnf with irevcm=8, d02nrf must be called to determine which column of the Jacobian is required and where it is to be placed in the array rwork (a argument of d02nmf or d02nnf).

4
References

See the D02M–N Sub-chapter Introduction.

5
Arguments

1:     j – IntegerOutput
On exit: the index j of the column of the Jacobian which is required.
2:     iplace – IntegerOutput
On exit: indicates which locations in the array rwork to fill with the jth column.
If iplace=1, the i,jth element of the Jacobian must be placed in rwork50+2×ldysav+i, otherwise the i,jth element must be placed in rwork50+ldysav+i.
If jceval='F', in the previous call to d02nuf, iplace=2 always, hence the jth column of the Jacobian must be placed in rwork50+ldysav+i, for i=1,2,,neq.
rwork, neq and ldysav are arguments of d02nmf and d02nnf.
3:     inform23 – Integer arrayCommunication Array
On entry: contains information supplied by the integrator.

6
Error Indicators and Warnings

None.

7
Accuracy

Not applicable.

8
Parallelism and Performance

d02nrf is not threaded in any implementation.

9
Further Comments

None.

10
Example

See Section 10 in d02nnf.