NAG FL Interface
d02nrf (ivp_​stiff_​sparjac_​enq)

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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 <nag.h>
void  d02nrf_ (Integer *j, Integer *iplace, const Integer inform[])
The routine may be called by the names d02nrf or nagf_ode_ivp_stiff_sparjac_enq.

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 (an argument of d02nmf or d02nnf).

4 References

See the D02M–N Sub-chapter Introduction.

5 Arguments

1: j Integer Output
On exit: the index j of the column of the Jacobian which is required.
2: iplace Integer Output
On exit: indicates which locations in the array rwork to fill with the jth column.
If iplace=1, the (i,j)th element of the Jacobian must be placed in rwork(50+2×ldysav+i), otherwise the (i,j)th element must be placed in rwork(50+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 rwork(50+ldysav+i), for i=1,2,,neq.
rwork, neq and ldysav are arguments of d02nmf and d02nnf.
3: inform(23) Integer array Communication Array
On entry: contains information supplied by the integrator.

6 Error Indicators and Warnings


7 Accuracy

Not applicable.

8 Parallelism and Performance

Background information to multithreading can be found in the Multithreading documentation.
d02nrf is not threaded in any implementation.

9 Further Comments


10 Example

See d02nnf.