This function is for internal use within other functions. A helper function to make the H matrix needed in ACT calculations
construct_h_matrix(eq)the equation dataframe being used in the analysis
the h matrix, which "symbolize the matrices of constant parameters" (see Heise, Expressive Order, p. 87)
eq <- get_equation(name = "us2010", type = "impressionabo", g = "average")
h_mat <- construct_h_matrix(eq = eq)