matlab求曲线拟合后的误差,matlab拟合曲线求参数？

代码示例matlab求曲线拟合后的误差：

令x＝(cos(k)./sin(k))./c，这个就是xdata向量

y=252/(2.016129032*10^bai9)*a*x^b

取log得到

log(y)=b*log(x)+log(252/(2.016129032*10^9)*a)

所以log(y)与log(x)是线性关系，用p=polyfit(log(xdata),log(y),1)求出

b=p(1);

a=exp(p(2))/252*(2.016129032*10^9);

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因为log(252/(2.016129032*10^9)*a)=p(2)

所以最终程序是如下：

clear

all

c=[2.7,2.8,2.9,3,3.1,3.2,3.45,3.7,3.95,4.2,4.45,4.7,4.95,5.2];

k=[0,47,93,140,186,279,372,465,558,651];

y=[18.98,27.35,34.86,38.52,38.44,37.73,38.43,43.87,42.77,46.22];

xdata=(cos(k)./sin(k))./c;

p=polyfit(log(xdata),log(y),1);

b=p(1);

a=exp(p(2))/252*(2.016129032*10^9);