nag_pde_interp_1d_fd (d03pzc) is an interpolation function for evaluating the solution of a system of partial differential equations (PDEs), at a set of user-specified points. The solution of the system of equations (possibly with coupled ordinary differential equations) must be computed using a finite difference scheme or a Keller box scheme on a set of mesh points. nag_pde_interp_1d_fd (d03pzc)
can then be employed to compute the solution at a set of points anywhere in the range of the mesh. It can also evaluate the first spatial derivative of the solution. It uses linear interpolation for approximating the solution.
Note: the arguments x, m, u, npts and npde must be supplied unchanged from the PDE function.
npde – IntegerInput
the number of PDEs.
m – IntegerInput
On entry: the coordinate system used. If the call to nag_pde_interp_1d_fd (d03pzc) follows one of the finite difference functions then m must be the same argument m as used in that call. For the Keller box scheme only Cartesian coordinate systems are valid and so mmust be set to zero. No check will be made by nag_pde_interp_1d_fd (d03pzc) in this case.
Indicates Cartesian coordinates.
Indicates cylindrical polar coordinates.
Indicates spherical polar coordinates.
following a finite difference function;
following a Keller box scheme function.
u – const doubleInput
On entry: the PDE part of the original solution returned in the argument u by the PDE function.