| lognormal_pred_kernel {mizer} | R Documentation |
Lognormal predation kernel
Description
This is the most commonly-used predation kernel. The log of the predator/prey mass ratio is normally distributed.
Usage
lognormal_pred_kernel(ppmr, beta, sigma)
Arguments
ppmr |
A vector of predator/prey size ratios |
beta |
The preferred predator/prey size ratio |
sigma |
The width parameter of the log-normal kernel |
Details
Writing the predator mass as w and the prey mass as w_p,
the feeding kernel is given as
\phi_i(w, w_p) =
\exp \left[ \frac{-(\ln(w / w_p / \beta_i))^2}{2\sigma_i^2} \right]
if w/w_p is larger than 1 and zero otherwise. Here \beta_i is the
preferred predator-prey mass ratio and \sigma_i determines the width of
the kernel. These two parameters need to be given in the species parameter
dataframe in the columns beta and sigma.
This function is called from setPredKernel() to set up the
predation kernel slots in a MizerParams object.
Value
A vector giving the value of the predation kernel at each of the
predator/prey mass ratios in the ppmr argument.
See Also
Other predation kernel:
box_pred_kernel(),
power_law_pred_kernel(),
truncated_lognormal_pred_kernel()