ACT Tips and Advice Post
"Q10: Are there any rules that allowed mathematics-related programs must follow? A: Programs must be written in the language of the calculator. Programs written in a different language, compiled, and loaded onto the calculator are not allowed. In this way, the programs can be examined on the calculator and will use calculator functions. Programs must not be lengthy. The limit is 25 logical lines of code. Programs cannot call another program. Techniques such as compressing code into a data statement are not allowed as a way of getting around this limit. Programs are allowed to change the value of system variables so that results may, for example, be graphed through the normal calculator graphing interface."
Pro tip: to include imaginary (nonreal) results, select "Mode" and change "Real" to "a+bi".