%Description: circleArea(radius) calculates the area of a circle
%Contract: number -> number
%Author: Terry Harvey  CISC106-10  TA: James Jamerson
%Examples:
%  circleArea(2) => 12.5664
%  circleArea(5) => 78.5398
%  circleArea(50) => 7853.98
function area = circleArea(radius)
  area = pi * radius^2;
  
%Note: HAS NO SCREEN INPUT OR OUTPUT, just does calculations and returns
%a value. Why? Keeping calculations separate makes it more likely that we
%can re-use code, and also makes code shorter, clearer, and easier to debug.