naginterfaces.library.ode.ivp_​stiff_​sparjac_​enq

naginterfaces.library.ode.ivp_stiff_sparjac_enq(comm)

ivp_stiff_sparjac_enq is an enquiry function for communicating with ivp_stiff_exp_revcom() or ivp_stiff_imp_revcom() when supplying columns of a sparse Jacobian matrix.

For full information please refer to the NAG Library document for d02nr

https://support.nag.com/numeric/nl/nagdoc_30.3/flhtml/d02/d02nrf.html

Parameters

commdict, communication object

Communication structure.

This argument must have been initialized by a prior call to ivp_stiff_exp_revcom() or ivp_stiff_imp_revcom().

Returns

jint

The index $j$ of the column of the Jacobian which is required.

iplaceint

Indicates which locations in the array $\text{rwork}$ to fill with the $j$th column.

If $iplace=1$, the $(i,j)$th element of the Jacobian must be placed in $\text{rwork}[50+2\times \text{ldysav}+i-1]$, otherwise the $(i,j)$th element must be placed in $\text{rwork}[50+\text{ldysav}+i-1]$.

If $\text{jceval}=\text{'F'}$, in the previous call to ivp_stiff_sparjac_setup(), $iplace=2$ always, hence the $j$th column of the Jacobian must be placed in $\text{rwork}[50+\text{ldysav}+\text{i}-1]$, for $\text{i}=1,2,\dots ,\text{neq}$.

$\text{rwork}$, $\text{neq}$ and $\text{ldysav}$ are arguments of ivp_stiff_exp_revcom() and ivp_stiff_imp_revcom().

Notes

No equivalent traditional C interface for this routine exists in the NAG Library.

ivp_stiff_sparjac_enq is required when ivp_stiff_exp_revcom() or ivp_stiff_imp_revcom() is being used with sparse matrix linear algebra. After an exit from ivp_stiff_exp_revcom() or ivp_stiff_imp_revcom() with $\text{irevcm}=8$, ivp_stiff_sparjac_enq must be called to determine which column of the Jacobian is required and where it is to be placed in the array $\text{rwork}$ (an argument of ivp_stiff_exp_revcom() or ivp_stiff_imp_revcom()).