The Heligman-Pollard build method fits the death probabilities to the parametric function $$ q_x = A^{(x+B)^C} + D e^{-E(\log(x/F)^2} + \frac{G H^x}{1+ K G H^x} $$ The first term models the mortality experienced by infants as they adapt to their environment. The last term models the aging process. The second term models the accident hump often seen in the late twenties. Fitting is done using a nonlinear optimization routine. The user can set the initial value of any of the parameters using an extrainfo string. For example setting the buildmethod to HELIGMAN_POLLARD:"F=20.0","E=5.0" will set the initial values of \(F\) and \(E\) to 20 and 5 respectively.