[求助]想了好长时间

function [hGraph, X, Y] = drawGraph(num)
% drawGraph.m
% Genial@edan
if nargin == 0
X = 1.0 * cos(0:pi/64:2*pi);
Y = 1.0 * sin(0:pi/64:2*pi);
hGraph = plot(X,Y);
axis equal;
elseif nargin == 1
if num~= round(num) || num < 2
error('Input must be an integer larger than 1!');
end
theta = 0: (2*pi)/num :2*pi;
X = 1.0 * cos(theta);
Y = 1.0 * sin(theta);
xcirl = 1.0 * cos(0:pi/64:2*pi);
ycirl = 1.0 * sin(0:pi/64:2*pi);
hGraph = plot(X, Y, xcirl, ycirl, '.');
axis equal;
else
error('Too many input arguments!');
end;