Evaluates the long memory trawl function
trawl_LM(x, alpha, H)
the argument at which the long memory trawl function will be evaluated
the parameter \(\alpha\) in the long memory trawl
the parameter \(H\) in the long memory trawl
the long memory trawl function evaluated at x
The trawl function is parametrised by the two parameters \(H> 1\) and \(\alpha > 0\) as follows: $$g(x) = (1-x/\alpha)^{-H}, \mbox{ for } x \le 0.$$