拟合n阶多项式

问题是 x 您使用的值是 xlim 其是长度为2的向量。您需要定义 x(x) 具有更多值的向量:

norm_dist = sort(5*randn(1,50) + (1:50)); %// example x values
norm_time = 5*randn(1,50) + (1:50).^2; %// example y values
x = linspace(min(norm_dist), max(norm_dist), 200); %// define x values for plot
coef_fit = polyfit(norm_dist,norm_time,7); 
y_fit = polyval(coef_fit,x); 
plot(x,y_fit,'r');
hold on
plot(norm_dist, norm_time, 'b.') %// plot original points for comparison