feat_growth: Adds an exponential growth or decline of the size of one
population to a model.
Description
This function changes the growth factor of a population at given
point in time (time). This factor than applies to the time
interval farther into the past from this point.
The population which growths/declines. Can be
"all" for all populations, or the number of one population.
time
The time at which the growth starts.
Value
The demographic model with a size change.
Details
The population size changes by factor exp(-alpha*t), where alpha
is the growth parameter and t is the time since the growth has
started. Hence, for positive alpha, the population will decline
backwards in time or grow forwards in time. Similar, will decline
in forwards time for a negative value of alpha.
If you want to add an instantaneous change of the population size,
then use the feat_size_change function.