y=[11.9 22.8 18.7 20.1 12.9 21.7 27.1 25.4 21.3 19.3 25.4 27.2 11.7 17.8 12.8 23.9 22.6 25.4 14.8 21.1];
x1=[19.5 24.7 30.7 29.8 19.1 25.6 31.4 27.9 22.1 25.5 31.1 30.4 18.7 19.7 14.6 29.5 27.7 30.2 22.7 25.2];
x2=[43.1 49.8 51.9 54.3 42.2 53.9 58.6 52.1 49.9 53.5 56.6 56.7 46.5 44.2 42.7 54.4 55.3 58.6 48.2 51];
x3=[29.1 28.2 37 31.1 30.9 23.7 27.6 30.6 23.2 24.8 30 28.3 23 28.6 21.3 30.1 25.6 24.6 27.1 27.5];
Y=y';
X=[ones(length(y),1),x1',x2',x3'];
[b,bint,r,rint,stats]=regress(Y,X)
这里到回归系数b
你自己画图吧