What dose Ei(1/1/10) means in matlab?

Hi there guys. I'm trying to evaluate this function (y=int(exp(-x)/x,a,inf)) using Matlab. when a= 0.1 ,I got y = Ei(1,1/10) and when a=1, y=Ei(1,1), anyone knows what this means? thanks.

[KSSV]

Why don't you post your code here?

Answer 1

[KSSV]

It is exponential integral. Read https://in.mathworks.com/help/matlab/ref/expint.html

[elgumatti]

thanks a lot Dr.