Question

请问matlab中nlinfit拟合函数怎么用

>> t = [0.25,0.5,0.75,1,1.5,2,2.5,3,3.5,4,4.5,5,6,7,8,9,10,11,12,13,14,15,16];
>> y = [30,68,75,82,82,77,68,68,58,51,50,41,38,35,28,25,18,15,12,10,7,7,4];

拟合出k1，k2，k3，函数是这样的：

Answer 1

t = [0.25,0.5,0.75,1,1.5,2,2.5,3,3.5,4,4.5,5,6,7,8,9,10,11,12,13,14,15,16];
y = [30,68,75,82,82,77,68,68,58,51,50,41,38,35,28,25,18,15,12,10,7,7,4];
mf=@(cs,t1)cs(1)*cs(3)/(cs(1)-cs(2))*(exp(-cs(2)*t1)-exp(-cs(1)*t1));
c=lsqcurvefit(mf,rand(3,1),t,y)
mf1=c(1)*c(3)/(c(1)-c(2))*(exp(-c(2)*t)-exp(-c(1)*t));
plot(t,y,'r*',t,mf1)

Answer 2

fun=inline('k(1)*k(3)/(k(1)-k(2))*(exp(-k(2)*t)-exp(-k(1)*t))','k','t');
k0=[1 0.5 1]; %初始条件

nlintool(t,y,fun,k0)