PCG package - release 1.0 at December 6, 2006

Description of the package:
---------------------------

The PCG package consists of the files listed and briefly described
below:

filename        contents of file

pcg.c           pcg main routine and some pcg specific internal routines.

utils.c         Common used utility routines by the NewtonLib iterative 
                linear solver codes:
                Dynamic memory allocation, computation of scalar products
                and norms, data output, parameter check and printout.
                
itlin.h         Common used type and macro definitions by the NewtonLib
                iterative linear solver codes.
                Should also be included in main programs which call
                NewtonLib iterative linear solver routines.

test_pcg.c      An example main program illustrating the usage of pcg.

Makefile        An input file to the UNIX make utility containing informa-
                tion how to build the executable program test_pcg.

readme          This information.

test_pcg_Darwin_out.nrm
                Example monitor output of program run of test_pcg.

test_pcg_Darwin_out.nrm
                Example data output of program run of test_pcg.

Note that in order to keep the archive at a reasonable size, 
further reference output files have been omitted.

The main program solves a test problem with a band matrix of bandwidth 5.
To make this matrix positive definite, choose the parameter diag in the file
test_pcg.c greater than 6.0. To build the executable program, you need
to compile and to link the files below:

test_pcg.c, pcg.c, utils.c

Under MacOSX (Darwin), SunOS, or Linux, simply type in:
make             -   to build program test_pcg.

Note that a few adaptations may be necessary to utilize the code for
your computer at hand. Please examine the itlin.h header file and adapt
the definitions of the macros SMALL and EPMACH, if needed.