Truncated lognormal predation kernel
Source:R/pred_kernel_funcs.R
truncated_lognormal_pred_kernel.RdThis is like the lognormal_pred_kernel() but with an imposed maximum
predator/prey mass ratio
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
Value
A vector giving the value of the predation kernel at each of the
predator/prey mass ratios in the ppmr argument.
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 between 1 and
\(\beta_i\exp(3\sigma_i)\)
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.
See also
Other predation kernel:
box_pred_kernel(),
lognormal_pred_kernel(),
power_law_pred_kernel()