command-line args in erl

[Wes James]

I am running through the mandelbrot example from:

http://projects.trapexit.org/web/#/web/project/github::ghulette::mandelbrot-erlang

and it has:

main([WArg,HArg]) ->.....

so you can provide command-line args like main 200 200, but how do you
do provide command line args in erl?

render:main([200,200]).

spits out:

** exception error: bad argument
     in function  atom_to_list/1
        called as atom_to_list(200)
     in call from render:main/1

what should main(??) look like?

thx,

-wes