code: public static boolean cs_lusol(int order, Dcs A, double[] b, double tol) {
          double[] x;
          Dcss S;
          Dcsn N;
          int n;
          boolean ok;
          if (!Dcs_util.CS_CSC(A) || b == null)
              return (false); /* check inputs */
          n = A.n;
          S = Dcs_sqr.cs_sqr(order, A, false); /* ordering and symbolic analysis */
          N = Dcs_lu.cs_lu(A, S, tol); /* numeric LU factorization */
          x = new double[n]; /* get workspace */
          ok = (S != null && N != null);
          if (ok) {
              Dcs_ipvec.cs_ipvec(N.pinv, b, x, n); /* x = b(p) */
              Dcs_lsolve.cs_lsolve(N.L, x); /* x = L\x */
              Dcs_usolve.cs_usolve(N.U, x); /* x = U\x */
              Dcs_ipvec.cs_ipvec(S.q, x, b, n); /* b(q) = x */
          }
          return (ok);
      }
docs: Solves Ax=b, where A is square and nonsingular. b overwritten with
  solution. Partial pivoting if tol = 1.
  
  @param order
  ordering method to use (0 to 3)
  @param A
  column-compressed matrix
  @param b
  size n, b on input, x on output
  @param tol
  partial pivoting tolerance
  @return true if successful, false on error