[交流] 【求助】polyfit的拟合效果不好，应该怎么修改？【已解决】

function dpolydengyaxuanzexing(n)
clc;
x=[238,258,278,298,318,338,358];
y1=[2.409,4.219,5.553,9.241,23.425,23.75,25.142];
y2=[3.060,5.270,9.421,13.423,25.909,31.125,31.833];
y3=[3.393,5.452,9.077,11.5,25.454,29.315,29.333];
y4=[3.803,5.381,7.078,9.667,25.3,28.5,28.666];
plot(x,y1,'gx')
hold on
plot(x,y2,'b*')
hold on
plot(x,y3,'r+')
hold on
plot(x,y4,'mo')
xlabel('temperature(K)');ylabel('adsorption capacity(mmol/g)');
p1=polyfit(x,y1,n);
p2=polyfit(x,y2,n);
p3=polyfit(x,y3,n);
p4=polyfit(x,y4,n);
y1=polyval(p1,x);
y2=polyval(p2,x);
y3=polyval(p3,x);
y4=polyval(p4,x);
plot(x,y1,'g-');
hold on
plot(x,y2,'b-')
hold on
plot(x,y3,'r-')
hold on
plot(x,y4,'m-')
legend('100kpa in MCM-41 without APTS','100kpa in MCM-41 with 15APTS',...
    '100kpa in MCM-41 with 30APTS','100kpa in MCM-41 with 45APTS');
hold off
end

Originally posted by zyj8119 at 2010-11-29 12:38:24:
[code]function dpolydengyaxuanzexing(n)
clc;
x=[238,258,278,298,318,338,358];
y1=[2.409,4.219,5.553,9.241,23.425,23.75,25.142];
y2=[3.060,5.270,9.421,13.423,25.909,31.125,31.833];
y3=[3.393,5. ...

Originally posted by change0618 at 2010-11-30 16:02:30:
N的值越大出现的龙格现象越严重，你只是显示了原数据点的图，并没有显示全区间的曲线。下面的就是n=6时的拟合图形

Originally posted by change0618 at 2010-11-30 16:15:56:
因为他只画了六个拟合值的折线图，n=6时，拟合值跟数据点基本重合，但是非数据点就不怎么好了