高次拟合问题

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1、第一类»x=l:l:12;»y二[66.4366.5167.5767.8867.4867.0566.7966.6266.4866.3566.1666.16];»p=polyfit(x,y,l1)Warning:Polynomialisbadlyconditioned.RemoverepeateddatapointsortrycenteringandscalingasdescribedinHELPPOLYFIT.>Inpolyfitat81p=Columns1through90.0000-0.00000.0002-0.00490.0629-0.53953.1259

2、-12.026829.3677Columns10through12-42.003731.148257.3000»n=l:0.05:12;»m=polyval(p,n);»plot(x,y?or);»holdon;»plot(n5m/rJ)»a=[0.0()0()-0.00000.0002-0.00490.0629-0.53953」259-12.026829.3677-42.003731.148257.3000];»y=0;»x=2;»fori=l:l:12y=y4-a(i)*xA(12-i);end;»y第二类»x=l:l:12;»y二［24.9424.9225

3、.1925.1624.724.424.2224.023.8223.6723.4523.37J;»p=polyfit(x,y,l1)Warning:Polynomialisbadlyconditioned.RemoverepeateddatapointsortrycenteringandscalingasdescribedinHELPPOLYFIT.>Inpolyfitat81p=Columns1through90.0000-0.00000.0003-0.00700.0947-0.85655.2280・21.331656.3340Columns10through1

4、2・90.48497&5530-2.5900»n=l:0.05:12;»m=polyval(p,n);»plot(x,y?or);»holdon;»plot(n,m,T」)第三类»x=l:l:12;»y二[8.598.699.259.349.048.958.948.868.768.638.548.84];»p=polyfit(x,y,ll)Warning:Polynomialisbadlyconditioned.RemoverepeateddatapointsortrycenteringandscalingasdescribedinHELPPOLYFIT.>In

5、polyfitat81P=Columns1through90.0000-0.00000.0006-0.01160.1476-1.26197.3099・28.410271.7105Columns10through12-110.426392.3713・22.8400»n=1:0.05:12;»m=polyval(p,n);»plot(x,y,'o');»holdon;»plot（n,m,T〕）