Return the SIPw model variables as a list, returned from Update_Xt.SIPw

This method dispatches on the type of `pars$Xpar`

# S3 method for SIPw
put_Xvars(Xvars, y, pars, i)

Arguments

Xvars

the X variables to insert into y

y

the variables

pars

an xds object

i

the host species index

Value

a [list]