docs: public void applyQ( ZMatrixRMaj A ) {
          if( A.numRows != numRows )
              throw new IllegalArgumentException("A must have at least "+numRows+" rows.");
  
          for( int j = minLength-1; j >= 0; j-- ) {
              int diagIndex = (j*numRows+j)*2;
              double realBefore = QR.data[diagIndex];
              double imagBefore = QR.data[diagIndex+1];
  
              QR.data[diagIndex] = 1;
              QR.data[diagIndex+1] = 0;
  
              QrHelperFunctions_ZDRM.rank1UpdateMultR(A, QR.data, j * numRows, gammas[j], 0, j, numRows, v);
  
              QR.data[diagIndex] = realBefore;
              QR.data[diagIndex+1] = imagBefore;
          }
      }