x=[20,40,60,80,100,110,120,130,140,150,160,170,180,190,200];
y=[15.75,21.27,26.81,32.38,37.99,40.81,43.62,46.45,49.28,52.13,54.88,57.83,60.84,63.57,66.40];
a = polyfit(x, y, 2);%进行2次拟合,a是多项式前面的值。
a1 = polyval(a, x);%得到拟合后的新值
plot(x,a1,'r');
grid on
我试过了,能用,不知道是不是你要的。这是二次拟合曲线