matlab单位抛物线响应,抛物线拟合的matlab问题（求助）。。。

clc;clear;

a=[1182.87 611.92 4463

1202.86 451.82 4463

1133.63 655.28 4443

1206.68 396.5 4443

1150.43 705.32 4423

1202.85 362.19 4423

1130.42 752.99 4403

1198.09 317.4 4403

1064.66 886.41 4343

1186.65 265.93 4343

1039.88 930.26 4303

1168.54 183.01 4303

1010.32 976.01 4263

1144.71 115.29 4263

996.97 996.97 4223

1124.69 66.72 4223 ];

x=a(:,1);

y=a(:,2);

z=a(:,3);

x1=x.*x;

y1=y.*y;

n=[ones(16,1),x,y,x1,y1];

[b,bint,r,rint,s]=regress(z,n)

b =

3344.5643678505

1.1863635529188

1.06237879512755

-0.000423283683249103

-0.000935949642143837

bint =

-312.150806263985            7001.279541965

-4.705138953335          7.07786605917261