D03PYF may be used in conjunction with either
D03PDF/D03PDA or
D03PJF/D03PJA. It computes the solution and its first derivative at user-specified points in the spatial coordinate.
SUBROUTINE D03PYF ( |
NPDE, U, NBKPTS, XBKPTS, NPOLY, NPTS, XP, INTPTS, ITYPE, UP, RSAVE, LRSAVE, IFAIL) |
INTEGER |
NPDE, NBKPTS, NPOLY, NPTS, INTPTS, ITYPE, LRSAVE, IFAIL |
REAL (KIND=nag_wp) |
U(NPDE,NPTS), XBKPTS(NBKPTS), XP(INTPTS), UP(NPDE,INTPTS,ITYPE), RSAVE(LRSAVE) |
|
D03PYF is an interpolation routine for evaluating the solution of a system of partial differential equations (PDEs), or the PDE components of a system of PDEs with coupled ordinary differential equations (ODEs), at a set of user-specified points. The solution of a system of equations can be computed using
D03PDF/D03PDA or
D03PJF/D03PJA on a set of mesh points; D03PYF can then be employed to compute the solution at a set of points other than those originally used in
D03PDF/D03PDA or
D03PJF/D03PJA. It can also evaluate the first derivative of the solution.
Polynomial interpolation is used between each of the break points
XBKPTSi, for
i=1,2,…,NBKPTS. When the derivative is needed (
ITYPE=2), the array
XPINTPTS must not contain any of the break points, as the method, and consequently the interpolation scheme, assumes that only the solution is continuous at these points.
None.
Note: the parameters
U,
NPTS,
NPDE,
XBKPTS,
NBKPTS,
RSAVE and
LRSAVE must be supplied unchanged from either
D03PDF/D03PDA or
D03PJF/D03PJA.
If on entry
IFAIL=0 or
-1, explanatory error messages are output on the current error message unit (as defined by
X04AAF).
None.