Matlab:非线性曲线拟合
- % Assume you determined xdata and ydata experimentally
- function logistic_renkou
- clc
- clear all
- xdata = [1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 ...
- 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000];
- ydata = [3.9 5.3 7.2 9.6 12.9 17.1 23.2 31.4 38.6 50.2 62.9 76.0 ...
- 92.0 106.5 123.2 131.7 150.7 179.3 204.0 226.5 251.4 281.4];
- a0 = [400 0.02]; % 初始猜测值
- [a, resnorm] = lsqcurvefit(@logistic,a0,xdata,ydata)
- yfit = a(1)./(1+(a(1)/3.9-1)*exp(-a(2)*(xdata-1790)));
- plot(xdata,ydata,'*b',xdata,yfit,'-r')
- function y = logistic(a,xdata)
- y = a(1)./(1+(a(1)/3.9-1)*exp(-a(2)*(xdata-1790)));
以上代码,用lsqcurvefit函数,求解下列方程,返回的a包含了所求的方程参数。
xdata和ydata是需要拟合的x、y值。
- y = a(1)./(1+(a(1)/3.9-1)*exp(-a(2)*(xdata-1790)));