x=[1.14,1.28,1.43,1.85,2,2.09,2.8,3.9,4.28,5.94,7.41,12.64,20.78];
y=[0.98,1.1,1.85,3.18,3.35,3.8,6.13,10.15,12.05,21.75,32.07,55.94,64.28];
plot(x,y,'.')
hold on
fun=@(A,x)A(1)*(1-exp((-2*x.^2)/A(2)^2));
p=nlinfit(x,y,fun,[1;1])%p第1个值为A,第2个值为B
xx=min(x)*0.5:0.1:max(x)*1.2;
yy=fun(p,xx);
plot(xx,yy)