Re: defining a integer greater than one
- To: mathgroup at smc.vnet.net
- Subject: [mg117889] Re: defining a integer greater than one
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Sat, 2 Apr 2011 17:04:54 -0500 (EST)
On 4/2/11 at 2:41 AM, karina.erlang at yahoo.de (Karina Erlang) wrote:
>I am new to Mathematica and cannot seem to achieve the following. I
>want to integrate an expression but Mathematica gives me a
>nonsensical if answer. (If Re(n)>1 then etc). How can I define n
>being greater than one before that integration. I can only achieve
>to make it an integer with the Element[] function.
You really need to post the details of what you are trying to do
with the Mathematica code to get answers that best apply to what
you are attempting. Meanwhile, look at the documentation for
Assuming. For example,
In[6]:= Assuming[ a > 0 && a s < 1,
Integrate[Exp[s t] Exp[-t/a]/a, {t, 0, Infinity}]]
Out[6]= 1/(1 - a*s)
Contrast that with the result you get from
Integrate[Exp[s t] Exp[-t/a]/a, {t, 0, Infinity}]