| truncated_lognormal_pred_kernel {mizer} | R Documentation |
Truncated lognormal predation kernel
Description
This is like the lognormal_pred_kernel() but with an imposed maximum
predator/prey mass ratio
Usage
truncated_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 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.
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(),
lognormal_pred_kernel(),
power_law_pred_kernel()