搜搜考试网怎样用 样条拟合 求函数表达式?急
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怎样用 样条拟合 求函数表达式?急
x=[385,560,621,655,676,695,711,728,750,776,806,837,858,880,900,923,943,982,1040,1120,1352];
y=[0.3,0.7,1,1.2,1.35,1.5,1.65,1.8,2,2.15,2.22,2.10,1.95,1.8,1.65,1.5,1.35,1.2,1,0.8,0.5];
by the way 用多项式拟合不了 a=polyfit(x,y,20)
运行后显示
Warning:Polynomial is badly conditioned.Remove repeated data points
or try centering and scaling as described in HELP POLYFIT.
> In polyfit at 79
a =
1.0e+009 *
Columns 1 through 9
0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0000 -0.0000
Columns 10 through 18
0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000
Columns 19 through 21
0.0020 -0.1157 1.6105
用b样条拟合怎样求函数表达式?3Q~
x=[385,560,621,655,676,695,711,728,750,776,806,837,858,880,900,923,943,982,1040,1120,1352];
y=[0.3,0.7,1,1.2,1.35,1.5,1.65,1.8,2,2.15,2.22,2.10,1.95,1.8,1.65,1.5,1.35,1.2,1,0.8,0.5];
by the way 用多项式拟合不了 a=polyfit(x,y,20)
运行后显示
Warning:Polynomial is badly conditioned.Remove repeated data points
or try centering and scaling as described in HELP POLYFIT.
> In polyfit at 79
a =
1.0e+009 *
Columns 1 through 9
0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0000 -0.0000
Columns 10 through 18
0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000
Columns 19 through 21
0.0020 -0.1157 1.6105
用b样条拟合怎样求函数表达式?3Q~
设满足条件的点的坐标为(X,Y); 那么根据点与点的距离公式 到（1,0）和（-1,0）距离的和等于4的点的集合为:{(X,Y)|根号((X+1)^2+Y^2)+根号((X-1)^2+Y^2=4}