source: git/kernel/gfan.cc @ 2c6535

/*
Compute the Gröbner fan of an ideal
*/

#include "mod2.h"
#include "kstd1.h"
#include "intvec.h"
#include "polys.h"
#include "ideals.h"

#ifndef gfan_DEBUG
#define gfan_DEBUG
#endif

ideal getGB(ideal inputIdeal)
{
        #ifdef gfan_DEBUG
        printf("Now in getGB\n");
        #endif

        ideal gb;
        gb=kStd(inputIdeal,NULL,testHomog,NULL); //Possible to call without testHomog/isHomog?
        idSkipZeroes(gb); //Get rid of zero entries

        return gb;
}

/****** getWallIneq computes the inequalities ***/
/*INPUT_TYPE: ideal                             */
/*RETURN_TYPE: matrix                           */
/************************************************/
void getWallIneq(ideal I)
{
        #ifdef gfan_DEBUG
        printf("Computing Inequalities...\n");
        #endif

        // Exponentenvektor
        Exponent_t leadexp,aktexp,diffexp;
        poly aktpoly;

        int lengthGB=IDELEMS(I);
        printf("The Gröbner basis has %i elements\n",lengthGB);

        // We loop through each g\in GB
        for (int i=0; i<IDELEMS(I); i++)
        {
                aktpoly=(poly)I->m[i];
                leadexp = pGetExp(aktpoly,1); //get the exp.vect of leading monomial
                for (int j=2;j<=pLength(aktpoly);j++)
                {
                        aktexp=pGetExp(aktpoly,j);
                        //diffexp=pSubExp(aktpoly, leadexp,aktexp); //Dang! => runtime error
                        //printf("Exponentenvektor=%i\n",expmark);
                        //printf("Diff=%i\n",expmark-pGetExp(aktpoly,j));
                }
                int pCompCount;
                pCompCount=pLength(aktpoly);
                printf("Poly No. %i has %i components\n",i,pCompCount);
        } //for
        //res=(ideal)aktpoly;
        //return res;
}

ideal gfan(ideal inputIdeal)
{
        #ifdef gfan_DEBUG
        printf("Now in subroutine gfan\n");
        #endif
        ideal res;
        matrix ineq; //Matrix containing the boundary inequalities

        res=getGB(inputIdeal);
        getWallIneq(res);
        return res;
}