code: @Override
      public boolean setA(DMatrixRBlock A) {
          // Extract a lower triangular solution
          if( !decomposer.decompose(A) )
              return false;
  
          blockLength = A.blockLength;
  
          return true;
      }
docs: Decomposes and overwrites the input matrix.
  
  @param A Semi-Positive Definite (SPD) system matrix. Modified. Reference saved.
  @return If the matrix can be decomposed.  Will always return false of not SPD.