function [area] = circle_area (radius)
% circle_area calculates the area of a circle from the radius.
%   Input arguments:
%     radius = radius of a circle 
%   Output arguments:
%     area = area of the circle

% This is an example of a MATLAB "function" file
%
% Programmer: Dick Furnstahl  furnstahl.1@osu.edu
%
% Revision history:
%   20-Mar-2005 -- original version for Physics 263
%

% calculate the area (the ";" at the end suppresses the output)
area = pi * radius^2;