d02pjf evaluates the interpolant calculated by
d02phf, following an integration step performed by
d02pgf to solve an initial value problem.
When integrating using the reverse communication Runge–Kutta integrator
d02pgf, the solution or its derivatives can be obtained inexpensively between steps by interpolation.
d02phf is called after a step by
d02pgf from a previous value of
$t$ (
$={t}_{k1}$) to its current value,
$t={t}_{k}$ (i.e., a
$k$th successful timestep has been taken).
d02pjf can then be called to evaluate interpolated approximations of the function or its derivatives at any value of
$t$ in the interval
$\left({t}_{k1},{t}_{k}\right)$.
Brankin R W, Gladwell I and Shampine L F (1991) RKSUITE: A suite of Runge–Kutta codes for the initial value problems for ODEs SoftReport 91S1 Southern Methodist University
If on entry
${\mathbf{ifail}}=0$ or
$1$, explanatory error messages are output on the current error message unit (as defined by
x04aaf).
 ${\mathbf{ifail}}=1$

On entry, a previous call to the setup routine has not been made or the communication arrays have become corrupted, or a catastrophic error has already been detected elsewhere.
You cannot continue integrating the problem.
On entry, ${\mathbf{ideriv}}=\u2329\mathit{\text{value}}\u232a$.
Constraint: ${\mathbf{ideriv}}=0$ or $1$.
On entry, ${\mathbf{lwcomm}}=\u2329\mathit{\text{value}}\u232a$, ${\mathbf{n}}=\u2329\mathit{\text{value}}\u232a$ and ${\mathbf{nwant}}=\u2329\mathit{\text{value}}\u232a$.
Constraint: for ${\mathbf{method}}=2$ or $2$, ${\mathbf{lwcomm}}\ge {\mathbf{n}}+\mathrm{max}\phantom{\rule{0.125em}{0ex}}\left({\mathbf{n}},5\times {\mathbf{nwant}}\right)$.
On entry, ${\mathbf{lwcomm}}=\u2329\mathit{\text{value}}\u232a$.
Constraint: for ${\mathbf{method}}=1$ or $1$, ${\mathbf{lwcomm}}\ge 1$.
On entry, ${\mathbf{lwcomm}}=\u2329\mathit{\text{value}}\u232a$ and ${\mathbf{nwant}}=\u2329\mathit{\text{value}}\u232a$.
Constraint: for ${\mathbf{method}}=3$ or $3$, ${\mathbf{lwcomm}}\ge 8\times {\mathbf{nwant}}$.
On entry, ${\mathbf{n}}=\u2329\mathit{\text{value}}\u232a$, but the value passed to the setup routine was ${\mathbf{n}}=\u2329\mathit{\text{value}}\u232a$.
On entry,
${\mathbf{nwant}}=\u2329\mathit{\text{value}}\u232a$, but on interpolation setup
${\mathbf{nwant}}=\u2329\mathit{\text{value}}\u232a$.
Constraint:
nwant must be unchanged from setup.
The previous call to the interpolation setup routine returned an error.
You cannot call this routine before you have called the interpolation setup.
The computed values will be of a similar accuracy to that computed by
d02pgf.
None.