裝修正有序多項式

Question

我試圖繪製迴歸曲線：

coef_fit = polyfit(norm_dist,norm_time,7); 
y_fit = polyval(coef_fit,xlim); 
plot(xlim,y_fit,'r'); 

但它始終是繪製相應的我通過訂單的行。

Answer 1

問題是您使用的x值是輸出ot xlim，它是長度爲2的向量。你需要更多的價值定義x載體：

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