旭无双
2009-09-27, 19:06
刚用MATLAB，在做对3个点进行抛物线拟合，然后进行插值找到抛物线顶点（最大值点），可是遇到这样一个问题：
Warning: Polynomial is badly conditioned. Remove repeated data points
or try centering and scaling as described in HELP POLYFIT.
> In polyfit at 79
In lvbo at 116
ss=[x2-1,x2,x2+1];
tt=[uu(x2-1),uu(x2),uu(x2+1)];
（116—）p=polyfit(ss,tt,n);其中的ss=[3006 3007 3008] tt =240.37292002942124 243.01899011713977 241.8321667762827]
程序中n=2，我觉得可能是因为曲线对应的多项式次数不够，不过用三个点来确定一条二次抛物线完全合理的！！可是改为n=3时，又有这样的提示：
Warning: Polynomial is not unique; degree >= number of data points.
> In polyfit at 72：：
warning('MATLAB:polyfit:PolyNotUnique', ...
'Polynomial is not unique; degree >= number of data points.')
Warning: Polynomial is badly conditioned. Remove repeated data points
or try centering and scaling as described in HELP POLYFIT.
> In polyfit at 79
In lvbo at 116
ss=[x2-1,x2,x2+1];
tt=[uu(x2-1),uu(x2),uu(x2+1)];
（116—）p=polyfit(ss,tt,n);其中的ss=[3006 3007 3008] tt =240.37292002942124 243.01899011713977 241.8321667762827]
程序中n=2，我觉得可能是因为曲线对应的多项式次数不够，不过用三个点来确定一条二次抛物线完全合理的！！可是改为n=3时，又有这样的提示：
Warning: Polynomial is not unique; degree >= number of data points.
> In polyfit at 72：：
warning('MATLAB:polyfit:PolyNotUnique', ...
'Polynomial is not unique; degree >= number of data points.')