Geografic-Information-System/lib/gmath/README

Date: Wed, 27 Sep 2000 15:41:24 +0000
From: David D Gray <ddgray@armadce.demon.co.uk>

I have checked in the gmath stuff to CVS. This directory might later            
contain other kinds of generic routine (fft is one that comes to mind in        
view of the investigations into NR). But for now there is only the              
BLAS/LAPACK wrappers and supporting structure in la.c.                          
                                                                                
I thought to follow the libc in separating maths stuff to a separate            
directory, even though they are G_*() functions.        

I believe it is fairly intuitive to use - developers should use               
G_matrix_init() to create a matrix. A vector can be built with setting        
cols (or rows as appropriate) to 1. A G_vector_init() might be useful,       
but it would have to distinguish between a row and column vector, (is it     
needed?). Then use G_[set,get]_matrix_element() to set or retrieve            
elements. No-one should need to ever worry about Fortran peculiarities        
(like declaring doublereal variables, or calling a foo_() ).                  
                                                                              
Currently there are: add matrices A+B (doesn't use BLAS), multiply A.B,       
invert A^-1, solve simple linear system A.X=B for X given B. Others are      
easy to add as required.

David
-----------------------------------

Getting BLAS/LAPACK (one package):

http://netlib.bell-labs.com/netlib/master/readme.html
http://www.netlib.org

http://www.netlib.org/lapack/

Compiling of LAPACK (be sure to have "." in PATH):

Linux: 
  cd LAPACK
  cp INSTALL/make.inc.LINUX make.inc 
  #now edit Makefile and
  #comment line 11 and uncomment line 12 (to include "blaslib" compilation)
  #compile with
  make

Solaris:
  cd LAPACK
  cp INSTALL/make.inc.SUN4SOL2 make.inc
  #now edit Makefile and
  #comment line 11 and uncomment line 12 (to include "blaslib" compilation)
  #compile with
  make

etc.

See INSTALL/ for further platforms.

--------------------------------------------------------------------
Usage:

Sample Makefile:

MODULE_TOPDIR = /path/to/grass

PGM = test

LIBES = $(GMATHLIB) $(GISLIB)
DEPENDENCIES = $(GMATHLIB) $(GISLIB)

include $(MODULE_TOPDIR)/include/Make/Module.make


Sample module source:

#include <grass/config.h>
#include <grass/gis.h>
#include <grass/gmath.h>

int main (int argc, char *argv[])
{
    mat_struct *matrix;

    matrix = G_matrix_init (3, 3, 1);
    G_matrix_free (matrix);

    return 0;
}