This predation kernel is a power-law, with sigmoidal cut-offs at large and small predator/prey mass ratios.

power_law_pred_kernel(
ppmr,
kernel_exp,
kernel_l_l,
kernel_u_l,
kernel_l_r,
kernel_u_r
)

## Arguments

ppmr A vector of predator/prey size ratios at which to evaluate the predation kernel. The exponent of the power law The location of the left, rising sigmoid The shape of the left, rising sigmoid The location of the right, falling sigmoid The shape of the right, falling sigmoid

## Value

A vector giving the value of the predation kernel at each of the predator/prey mass ratios in the ppmr argument.

## Details

The return value is calculated as

 ppmr^kernel_exp / (1 + (exp(kernel_l_l) / ppmr)^kernel_u_l) / (1 + (ppmr / exp(kernel_l_r))^kernel_u_r) 

The parameters need to be given as columns in the species parameter dataframe.