D02ZAF calculates the weighted norm of the local error estimate from inside a
MONITR called from an integrator in
sub-chapter D02M–N (e.g., see
D02NBF).
D02ZAF is for use with the forward communication integrators
D02NBF,
D02NCF,
D02NDF,
D02NGF,
D02NHF and
D02NJF and the reverse communication integrators
D02NMF and
D02NNF. It must be used only inside
MONITR (if this option is selected) for the forward communication routines or on the equivalent return for the reverse communication routines. It may be used to evaluate the norm of the scaled local error estimate,
$\Vert v\Vert $, where the weights used are contained in
$w$ and the norm used is as defined by an earlier call to the integrator setup routine (
D02MVF,
D02NVF or
D02NWF). Its use is described under the description of
MONITR in the specifications for the forward communication integrators mentioned above.
None.
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).
D02ZAF should only be used within
MONITR associated with the integrators in
sub-chapter D02M–N (e.g., see
D02NBF). Its use and only valid calling sequence are fully documented in the description of
MONITR in the routine documents for the integrators.
This example solves the well-known stiff Robertson problem
over the range
$\left[0,10\right]$ with initial conditions
$a=1.0$ and
$b=c=0.0$ using scalar error control (
${\mathbf{ITOL}}=1$) and computation of the solution at
${\mathbf{TOUT}}=10.0$ with
TCRIT (e.g., see
D02MVF) set to
$10.0$ (
${\mathbf{ITASK}}=4$). A BDF integrator (setup routine
D02NVF) is used and a modified Newton method is selected. This example illustrates the use of D02ZAF within a monitor routine
MONITR to output intermediate results during the integration. The same problem is solved in the example program for
D02NBF where no monitoring was performed and so no intermediate solution information is output.