Trying to solve the parameters for an equation

There is a dataset for the following mathematical model, please use MATLAB to find these parameters a1、a2、b1 and b2

x=0:0.1:2

y=[xdata1 xdata2... xdata21]

y=a1*exp(b1*x)+a2*exp(b2*x)

I think it has something to do with fminsearch, but I don't know where to start

Answer 1

[Walter Roberson]

fun = @(ab) sum((ab(1)*exp(ab(3)*x) + ab(2) * exp(ab(4)*x) - y).^2)
ab0 = randn(1,4);
AB = fminsearch(fun, ab0);
a1 = AB(1); a2 = AB(2); b1 = AB(3); b2 = AB(4);

[Daniel Kuo]

What is the use of "randn"?

[Daniel Kuo]

So I know randn(1,4) give you four random numbers; but what is the use of that in this function?

[Daniel Kuo]

Nvm, I got it. Thanks m8, much love <3

[Walter Roberson]

In this context, ab0 is the starting point for the search. I did not want to presume that the values were positive.