logistic3 {lefko3} | R Documentation |
Two-parameter logistic function
Description
Function logistic3()
creates a vector of values produced by the
logistic function as applied with a user-specified time lag. The logistic
function is given as
\phi_{t+1} = \phi_t \lambda (1 - n_t / K)
. Here,
if no separate_N
vector is provided, then n_t = \phi_t
. If
\lambda
is not provided, then it defaults to 1.0
.
Usage
logistic3(
start_value,
alpha,
beta = 0,
lambda = 1,
time_steps = 100L,
time_lag = 1L,
pre0_subs = FALSE,
pre0_value = 0,
substoch = 0L,
separate_N = NULL
)
Arguments
start_value |
A positive number to start the return vector in time 0. |
alpha |
The carrying capacity K. |
beta |
If set to some positive number, then this number is the maximum
value of phi to enforce. Otherwise, equals |
lambda |
The value of the discrete population growth rate to use. Equal to the natural logarithm of the instantaneous growth rate, r. |
time_steps |
The number of time steps to run the projection. Must be a positive integer. |
time_lag |
A positive integer denoting the number of time steps back for the value of phi in the logistic function. |
pre0_subs |
A logical value indicating whether to use a number other
than that given in |
pre0_value |
A positive number to use for phi lagged from times prior
to time 0. Only used if |
substoch |
An integer value indicating the kind of substochasticity to
use. Values include: |
separate_N |
An optional numeric vector with values of N in each time, if phi is to be treated as different from N in the logistic model. |
Value
A numeric vector of values showing values projected under the- logistic function.
Examples
trial_run1 <- logistic3(1, alpha = 5)
plot(trial_run1)
trial_run2 <- logistic3(1, alpha = 5, beta = 5)
plot(trial_run2)
trial_run3 <- logistic3(1, alpha = 100)
plot(trial_run3)
trial_run4 <- logistic3(1, alpha = 100, beta = 50)
plot(trial_run4)
trial_run5 <- logistic3(1, alpha = 500)
plot(trial_run5)
trial_run6 <- logistic3(1, alpha = 500, beta = 501)
plot(trial_run6)
used_Ns <- c(10, 15, 12, 14, 14, 150, 15, 1, 5, 7, 9, 14, 13, 16, 17, 19,
25, 26)
trial_run7 <- logistic3(1, alpha = 500, beta = 501, separate_N = used_Ns)
plot(trial_run7)