code: public static Dcss cs_schol(int order, Dcs A) {
          int n, c[], post[], P[];
          Dcs C;
          Dcss S;
          if (!Dcs_util.CS_CSC(A))
              return (null); /* check inputs */
          n = A.n;
          S = new Dcss(); /* allocate result S */
          P = Dcs_amd.cs_amd(order, A); /* P = amd(A+A'), or natural */
          S.pinv = Dcs_pinv.cs_pinv(P, n); /* find inverse permutation */
          if (order != 0 && S.pinv == null)
              return null;
          C = Dcs_symperm.cs_symperm(A, S.pinv, false); /* C = spones(triu(A(P,P))) */
          S.parent = Dcs_etree.cs_etree(C, false); /* find etree of C */
          post = Dcs_post.cs_post(S.parent, n); /* postorder the etree */
          c = Dcs_counts.cs_counts(C, S.parent, post, false); /* find column counts of chol(C) */
          S.cp = new int[n + 1]; /* allocate result S.cp */
          S.unz = S.lnz = Dcs_cumsum.cs_cumsum(S.cp, c, n); /* find column pointers for L */
          return ((S.lnz >= 0) ? S : null);
      }
docs: Ordering and symbolic analysis for a Cholesky factorization.
  
  @param order
  ordering option (0 or 1)
  @param A
  column-compressed matrix
  @return symbolic analysis for Cholesky, null on error