Question about "Derivative of p_FinC in respect to 'interpolated' IMU pose"

[wxpiggy]

      MatrixXd dp_FinC_dI = MatrixXd::Zero(3, 6);
      dp_FinC_dI.block(0, 0, 3, 3) = R_ItoC * skew_x(p_FinI);
      dp_FinC_dI.block(0, 3, 3, 3) = -dp_FinC_dp_FinG;

Dear Author
I am new to SLAM area, but shouldn't it be dp_FinC_dI.block(0, 0, 3, 3) = - R_ItoC * skew_x(p_FinI);? with a '-'