I believe Equation 2.17 and the following unnumbered equation following are correct. This shows the coefficients in the sums should be indexed by the summation variable "j". In other words, 2.18 should change c_i --> c_j and similarly for the unnumbered equation following.
The index is correct again in 2.19.
I believe Equation 2.17 and the following unnumbered equation following are correct. This shows the coefficients in the sums should be indexed by the summation variable "j". In other words, 2.18 should change c_i --> c_j and similarly for the unnumbered equation following.
The index is correct again in 2.19.