docs: public static boolean cholU( DMatrix6x6 A ) {
  
          A.a11 = Math.sqrt(A.a11);
          A.a21 = 0;
          A.a31 = 0;
          A.a41 = 0;
          A.a51 = 0;
          A.a61 = 0;
          A.a12 = (A.a12)/A.a11;
          A.a22 = Math.sqrt(A.a22-A.a12*A.a12);
          A.a32 = 0;
          A.a42 = 0;
          A.a52 = 0;
          A.a62 = 0;
          A.a13 = (A.a13)/A.a11;
          A.a23 = (A.a23-A.a12*A.a13)/A.a22;
          A.a33 = Math.sqrt(A.a33-A.a13*A.a13-A.a23*A.a23);
          A.a43 = 0;
          A.a53 = 0;
          A.a63 = 0;
          A.a14 = (A.a14)/A.a11;
          A.a24 = (A.a24-A.a12*A.a14)/A.a22;
          A.a34 = (A.a34-A.a13*A.a14-A.a23*A.a24)/A.a33;
          A.a44 = Math.sqrt(A.a44-A.a14*A.a14-A.a24*A.a24-A.a34*A.a34);
          A.a54 = 0;
          A.a64 = 0;
          A.a15 = (A.a15)/A.a11;
          A.a25 = (A.a25-A.a12*A.a15)/A.a22;
          A.a35 = (A.a35-A.a13*A.a15-A.a23*A.a25)/A.a33;
          A.a45 = (A.a45-A.a14*A.a15-A.a24*A.a25-A.a34*A.a35)/A.a44;
          A.a55 = Math.sqrt(A.a55-A.a15*A.a15-A.a25*A.a25-A.a35*A.a35-A.a45*A.a45);
          A.a65 = 0;
          A.a16 = (A.a16)/A.a11;
          A.a26 = (A.a26-A.a12*A.a16)/A.a22;
          A.a36 = (A.a36-A.a13*A.a16-A.a23*A.a26)/A.a33;
          A.a46 = (A.a46-A.a14*A.a16-A.a24*A.a26-A.a34*A.a36)/A.a44;
          A.a56 = (A.a56-A.a15*A.a16-A.a25*A.a26-A.a35*A.a36-A.a45*A.a46)/A.a55;
          A.a66 = Math.sqrt(A.a66-A.a16*A.a16-A.a26*A.a26-A.a36*A.a36-A.a46*A.a46-A.a56*A.a56);
          return !UtilEjml.isUncountable(A.a66);
      }