# Integrating 1/x*e^x dx from 0 to s, how to do it

1. Sep 22, 2010

### smoodliar

Hi

I have an integral as follows,

int((1/x)exp(-x),x,0,s)

I want to integrate from [0,s).

My question is how to integrate without including s as the upper bound.

Any help will be appreciated

2. Sep 22, 2010

### Feldoh

Re: Integrals

Integrate from [0,s-a] in the limit as a -> 0?

3. Sep 22, 2010

### smoodliar

Re: Integrals

Hey

If the integral is the lower gamma incomplete function, which is

int(exp(-t)*t^(a-1),t,0,x)

how would I be able to evaluate the integral between [0,x-a) as a->0 ?

4. Sep 22, 2010

### sachinism

Re: Integrals

well u are right

but i dont know, his question doest sound too sensible to me

then by anser u gave it obviously means changing parameters of integration

5. Sep 22, 2010

### smoodliar

Re: Integrals

Hi sachinism

I hope I cleared up my question with my last post.

Any help will be great