void LpGlpk::_setCoeff(int row, int col, Value value) 

   {

     ///FIXME Of course this is not efficient at all, but GLPK knows not more.

     // First approach: get one row, apply changes and set it again

     //(one idea to improve this: maybe it is better to do this with 1 coloumn)

     int mem_length=2+lpx_get_num_cols(lp);

     int* indices = new int[mem_length];

     Value* values = new Value[mem_length];

     int length=lpx_get_mat_row(lp, row, indices, values);

     //The following code does not suppose that the elements of the array indices are sorted

     int i=1;

     bool found=false;

     while (i <= length && !found){

       if (indices[i]==col){

 	found = true;

 	values[i]=value;

       }

       ++i;

     }

     if (!found){

       ++length;

       indices[length]=col;

       values[length]=value;

     }

     lpx_set_mat_row(lp, row, length, indices, values);

     delete [] indices;

     delete [] values;

   }