画图，但是总遇到提示有问题，怎么回事？

代码如下：

u=[1.121053,1.052632,1.000000,0.947368,0.905263,0.852632,0.800000,0.747368,0.705263,0.652632,0.600000,0.547368,0.526316,0.505263,

0.484211,0.473684,0.463158,0.452632,0.442105,0.431579,0.421053,0.410526,0.400000,0.389474,0.378947,0.368421,0.357895,0.347368];

p=[0.484515,0.428333,0.412780,0.403545,0.400569,0.386055,0.386709,0.380415,0.375948,0.373822,0.374814,0.367592,0.366922,0.371988,

0.376991,0.382937,0.378579,0.377283,0.374799,0.375938,0.382451,0.380307,0.381883,0.383498,0.378111,0.395578,0.411276,0.421358];

q=[0.922466,0.736968,0.630898,0.531095,0.465205,0.404971,0.335861,0.285312,0.252639,0.216848,0.181531,0.167480,0.161788,0.157905,

0.154859,0.154340,0.157830,0.160153,0.159664,0.162969,0.170892,0.170493,0.173991,0.175285,0.179902,0.210816,0.241309,0.272170];

c1=polyfit(u,p,5);% 5次多项式拟合

x1=0:0.05:1.4;

y1=polyval(c1,x1);

z1=0.407*(x1.^0.074);

w1=-3*(x1.^3)+2*(x1.^2)+2*x1;

plot(x1,w1,'s-',x1,y1,'r-o',x1,z1,'g-.p');

axis([0 1.5 -2 1.5]);

xlabel('U(电压)');ylabel('P(有功功率)');

c2=polyfit(u,q,5);

x2=0:0.05:1.4;

y2=polyval(c2,x2,5);

z2=0.58*(x2.^1.39);

w2=(x2.^2)+x2-1;

figure(2)

plot(x2,y2,'r-o',x2,z2,'g-.p',x2,w2,'s-');

axis([0 1.5 -1 1.5]);

xlabel('U(电压)');ylabel('Q(无功功率)');

2013-12-30 15:09 上传