docs: public static double transposeTimes(final double[] v1, final double[] v2) {
      assert v2.length == v1.length : ERR_VEC_DIMENSIONS;
      double s = 0;
      for(int k = 0; k < v1.length; k++) {
        s += v1[k] * v2[k];
      }
      return s;
    }