huke2.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];
plot(x,f,'+'),
pause

x1=[1 2 4 7 9 ];
f1=[1.5 3.9 6.6 11.7 15.6 ];
k=x1'\f1';
xx1=0:0.1:9;
y1=k*xx1;
y10=k*9;
plot(x1,f1,'+',xx1,y1),
pause

x2=[9 12 13 15 17];
f2=[15.6 18.8 19.6 20.6 21.1];
u=f2-k*x2;
v=(x2/9).^2-2*x2/9+1;
a3=v'\u';
a1=a3/81;
a2=k-2*a3/9;
xx2=9:0.1:17;
y2=a1*xx2.^2+a2*xx2+a3;
y20=a1*81+a2*9+a3;
dy20=2*a1*9+a2;
plot(x2,f2,'+',xx2,y2),
k,y10,y20,dy20,a1,a2,a3
pause
plot(xx1,y1,xx2,y2,x,f,'+')