plot_rat: Line plots of rational functions
In weiyaw/blackbox: A SMC-SA Algorithm for Constrained Optimisation

Plot one or multiple rational functions, given a set of coefficients.

1	plot_rat(fs, gs, xlim = c(0, 10), sketch = TRUE, fine = 1000, ...)

`fs`	a matrix of numerator polynomial in ascending order representing, each column corresponds to a polynomial. (num mat)
`gs`	a matrix of denominator coefficients in ascending order, each column corresponds to a polynomial. (num mat)
`xlim`	the x-axis range to plot
`sketch`	if set to `TRUE`, this function add a rational function onto an existing plot, rather than creating a new graphical device.
`fine`	how many points between xlims?
`...`	optional graphical parameters to be passed to plot function.