huke3.m

matlab讲义

x=[1 2 4 7 9 12 13 15 17];
f=[1.5 3.9 6.6 11.7 15.6 18.8 19.6 20.6 21.1];
x1=[1 2 4 7 9 ];
f1=[1.5 3.9 6.6 11.7 15.6 ];
x2=[9 12 13 15 17];
f2=[15.6 18.8 19.6 20.6 21.1];
k=x1'\f1';
xx1=0:0.1:9;
y1=k*xx1;
y10=k*9;

u=f2-k*9;
v1=x2.^2-81;
v2=x2-9;
R=[v1' v2'];
a=R\u';
a1=a(1);a2=a(2);
xx2=9:0.1:17;
y2=a1*(xx2.^2-81)+a2*(xx2-9)+k*9;
subplot(1,2,1),
plot(xx1,y1,xx2,y2,x,f,'+')

uu=f2-k*x2;
v=(x2/9).^2-2*x2/9+1;
a3=v'\uu';
a1=a3/81;
a2=k-2*a3/9;
xx2=9:0.1:17;
yy2=a1*xx2.^2+a2*xx2+a3;
subplot(1,2,2),
plot(xx1,y1,xx2,yy2,x,f,'+')