急求助:源程序提示错误.怎么调用函数,具体步骤?

function [positions,ranges]=...
   cp1002_create_network(N,area_side,G)
for i=1:N
    positions(i,1)=rand*area_side;
    positions(i,2)=rand*area_side;
    j=1;
    for j=1:(i-1)
        ranges(i,j)=sqrt((positions(i,1)-...
            positions(j,1))^2+(positions(i,2)-...
            positions(j,2))^2;
        while(ranges(i,j)==0)
            X(i)=rand*50;
            Y(i)=rand*50;
            ranges(i,j)=sqrt((positions(i,1)-...
                positions(j,1))^2+(positions(i,2)-...
                positions(j,2))^2;
        end
        ranges(j,i)=ranges(i,j);
    end
end
if G
    scatter(positions(:,1),positions(:,2),'filled');
    axis([0 area_side 0 area_side]);
    xlable('X[m]');
    ylable('Y[m]');
    box on;
end
运行后提示错误
??? function [positions,ranges]=...
Error: Function definitions are not permitted at the prompt or in scripts.
麻烦高手指点一下,在matlab里怎么调用函数,具体步骤怎么做,十分感谢

[[it] 本帖最后由 snowfa 于 2008-11-11 08:07 编辑 [/it]]