Multigrid Control Package
This is a collection of Fortran77 routines for executing various
multigrid control algorithms, including V-cycles, W-cycles, C-cycles,
and the FMG algorithm. All are problem-independent, and can be accessed
via a single routine (mgs) which also can execute single-grid relaxation
for comparison.
The use of this code is illustrated by my Multigrid Poisson Solver listed
below.
Fortran 77 code:
single precision
or
double precision
Multigrid Solver for the 2D Poisson Problem
This Fortran77 routine solves the Poisson Problem on a two-dimensional
rectangle with Dirichlet boundary conditions via a multigrid method.
This uses Gauss-Seidel relaxation (red-black ordering) with half-injection
of residuals and bilinear interpolation of corrections in a V-cycle algorithm.
It works and is reasonably efficient, but is hardly general-purpose software.
I wrote it primarily as an example of a relatively simple approach to
programming multigrid methods in Fortran77; this approach separates the
problem-dependent and multigrid-specific code and allows the compiler to
handle the indexing on rectangular grids.
It comes with a simple main program and the V-cycle control algorithm from
my Multigrid Control Package listed above.
Fortran 77 code:
single precision
and
sample output