huiscliu / sxamg

Algebraic Multigrid (AMG) Solver Library

SXAMG

SXAMG is an Algebraic Multigrid Solver Library written by C. The initial code was from FASP (http://fasp.sourceforge.net/), a linear solver package that implemented Krylov solvers, preconditioners and AMG solvers. The SXAMG was extracted from FASP to serve as a standalone AMG solver.

How-to

Configuration

The simplest way to configure is to run command:

./configure

This command will detect system and set default options.

Options

Run command:

./configure --help

Compilation

After configuration, a simple make command can compile the package:

make

Installation

Run command:

make install

The package will be installed to a directory. The default is /usr/local/sxamg/. A different directory can be set by --prefix=DIR.

Demo

The following codes show how to use SXAMG as a solver.

{
    SX_AMG_PARS pars;
    SX_MAT A;
    SX_VEC b, x;
    int verb = 2;
    SX_RTN rtn;
    
    /* default pars */
    sx_amg_pars_init(&pars);

    /* redefine parameters */
    pars.maxit = 1000;
    pars.verb = 2;
    
    /* set A, b, initial x */
    ....
    
    /* solve the system */
    rtn = sx_solver_amg(&A, &x, &b, &pars);
    
    /* free memory */
    sx_mat_destroy(&A);
    sx_vec_destroy(&b);
    sx_vec_destroy(&x);
}

sxamg's Issues

Meaning of the variable 'verb'

Hi,
When I was reading your code, I saw a variable verb. I'm sorry I didn't understand the function of the variable. Could you please tell me the details of the variable?
For example, in example/amg.c
pars.verb = 3;

Thanks!

Plugin as a preconditioner

Hi, Dr. Liu,
I like your refactorization software sxamg. I am trying to plugin it to solve a 3D Maxwell equation (complex in frequency domain which has been converted into a rea-valued linear system Ax=bl). Unfortunately, the code runs into AMG setup stage without exist for hours.
I do not know why, because I was able to run your examples of 3D Poisson equation successfully. Can you give me some help?

I think you have made a lot of optimization for sxamg in grid coarsening. But I was unable to figure out what has been implemented exactly. Typically, op-coarsen.c is the one I am looking at. Can you provide a reference or paper which you were following?

Any help would be highly appreciated!

Best regards,
Pengliang

install failed problem

Hi,
I want to learn and use the sxamg you developed, but after I type make install, there are some errors：

make[1]: Entering directory '/home/txt/Downloads/sxamg-master/src'
make[1]: Nothing to be done for 'default'.
make[1]: Leaving directory '/home/txt/Downloads/sxamg-master/src'
cp: cannot stat 'lib/libsxamg.a': No such file or directory
Makefile:28: recipe for target 'install' failed
make: *** [install] Error 1

Whether I use ./configure, make, sudo make install or ./configure --prefix/xx/xx, make, make install will have this problem, the installation directory has only one empty folder lib