get_immig_rate: Calculate immigration rate
In joshwlambert/DAISIEsim:

Description Usage Arguments Author(s) References See Also

Internal function. Calculates the immigration rate given the current number of species in the system, the carrying capacity

1 2	get_immig_rate(timeval, totaltime, gam, Apars, divdep, island_ontogeny, sea_level, island_spec, K, mainland_n)

`timeval`	current time of simulation
`totaltime`	total time of simulation
`gam`	per capita immigration rate
`Apars`	a named list containing area parameters as created by create_area_params: [1]: maximum area [2]: value from 0 to 1 indicating where in the island's history the peak area is achieved [3]: sharpness of peak [4]: total island age
`island_ontogeny`	a string describing the type of island ontogeny. Can be `NULL`, `"beta"` for a beta function describing area through time, or `"linear"` for a linear function
`island_spec`	matrix with current state of system
`K`	carrying capacity
`mainland_n`	total number of species present in the mainland

Pedro Neves

Valente, Luis M., Rampal S. Etienne, and Albert B. Phillimore. "The effects of island ontogeny on species diversity and phylogeny." Proceedings of the Royal Society of London B: Biological Sciences 281.1784 (2014): 20133227.

Does the same as DAISIE_calc_clade_imm_rate

Other rates calculation: get_ana_rate, get_ext_rate, get_t_hor, island_area, update_rates