User:Karthik0112358/massmatrix

//Include necessary headers.
int massmatrix(slv_system_t sys,  struct massmatrixStruct *mass, const rel_filter_t *rfilter, const var_filter_t *vfilter){
// here there might be some more parameters to accept. I haven't figured it out yet. Although I think some filter parameters need to be shaken up a little.
   struct var_variable **svars;
   struct rel_relation **srels;
   mtx_coord_t coord;
//the above declarations are self explanatory.
   int i,j,n,nsr,nsv,nr,nv;
//first count the rels
   nsr = slv_get_num_solvers_rels(sys);
   nr = slv_count_solvers_rels(sys,rfilter);
   srels = slv_get_solvers_rel_list(sys);
//and vars
   nsv = slv_get_num_solvers_vars(sys);
   nv = slv_count_solvers_vars(sys,vfilter);
   svars = slv_get_solvers_var_list(sys);
//allocate space for lists
   mass->vars = ASC_NEW_ARRAY(struct var_variable*, nv);
   mass->rels = ASC_NEW_ARRAY(struct rel_relation*, nr);
   vartocol = ASC_NEW_ARRAY(int,nsv);
//So till here code looks neat. Gets slightly messy from now on.
//now create a the lists of vars and rels, and temp mapping array
   n = 0;
   for(i=0;i<nsr;++i){
      if(rel_apply_filter(srels[i],rfilter)){
         mass->rels[n++] = srels[i];
      }
   }
   asc_assert(n==nr);
   n = 0;
   for(i=0;i<nsv;++i){
      if(var_apply_filter(svars[i],vfilter)){         
         vartocol[i]=n;
         mass->vars[n++] = svars[i];
      }else{
         vartocol[i]=-1;
      }
   }
   asc_assert(n==nv);
//now create a matrix
   mass->M = mtx_create();
   mtx_set_order(mass->M, MAX(nv,nr));
   for(i=0;i<nr;++i){
//Need to write a function, so that I can call it here which basically takes the relation and finds the coefficients of all first order derivatives. 
      for(j=0;j<n;++j){
         mtx_set_value(mass->M,mtx_coord(&coord,i,vartocol[/* need to figure equivalent here*/]),/*put the equivalent figured here too*/);
      }
//Check for errors in doing above 2 operations via function call
   }
   mass->n_rels = nr;
   mass->n_vars = nv;
}
/*
I would define the structure massmatrix in the header as:
struct massmatrixStruct{
   mtx_matrix_t M;
   struct rel_relation **rels;
   struct var_variable **vars;
   int n_rels, n_vars;
}; 
*/