docs: public static boolean cholL( DMatrix2x2 A ) {
  
          A.a11 = Math.sqrt(A.a11);
          A.a12 = 0;
          A.a21 = (A.a21)/A.a11;
          A.a22 = Math.sqrt(A.a22-A.a21*A.a21);
          return !UtilEjml.isUncountable(A.a22);
      }