Add lines for the density of infected individuals for the SIR model

Add lines for the density of infected individuals for the SIR model

xde_lines_X_SIR(XH, pars, clrs = c("black", "darkred", "darkblue"), llty = 1)

Arguments

XH

a list with the outputs of parse_deout_X_SIS

pars

a list that defines an `ramp.xde` model (*e.g.*, generated by `xde_setup()`)

clrs

a vector of colors

llty

an integer (or integers) to set the `lty` for plotting