std::cout<<"Error in IRREF_Jordan(ExactConstraintSatisfaction.cc) : couldn't find a pivot_col."<<std::endl;
for(inti=k-1;i>=0;i--){//eliminate row i with row k
b.coeffRef(i)=(A.coeff(k,pivot_col)*b.coeff(i)-A.coeff(i,pivot_col)*b.coeff(k));//do it in this order, so we don't delete entries in A for the computation of b
eliminate_row(A,i,k);
if(A.coeff(i,pivot_col)==0)
continue;
if(b.coeff(i)!=0||b.coeff(k)!=0)
b.coeffRef(i)=(A.coeff(k,pivot_col)*b.coeff(i)-A.coeff(i,pivot_col)*b.coeff(k));//do it in this order, so we don't delete entries in A for the computation of b
eliminate_row(A,i,k,pivot_col);
intgcdValue=gcd_row(A.row(i),b.coeffRef(i));//compute the gcd to make the values as small as possible