Hi,

try

Assuming[m \[Element] Integers && m > 0, Integrate[t Sin[2 m t], {t, 0, Pi}]]

It also works with $n$, but I usually try to avoid $n$ because there is a function $N$ and sometimes that can be confusing.

Alternatively, you can first integrate and then simplify using assumptions:

FullSimplify[Integrate[t Sin[2 n t], {t, 0, Pi}], Assumptions -> n \[Element] Integers && n > 0]

Cheers,

Marco

Hi Milos,

it's not really magic -just syntax.

PS : I read your post with Outlook and thus, n apparates as dollar-n-dollar. Sorry, but I'm still curious abour the perhaps dysfunction of (Elements->..) ?

I don't use Outlook, but the $n$ comes from the markdown syntax that the community uses. It's a bit like Latex and I instinctively use it for formatting text. If you read the post in a browser it will not show up. Regarding the Element function I think it works just fine.

This function shows you what is going on in my line of code:

Assuming[m \[Element] Integers && m > 0, Integrate[t Sin[2 m t], {t, 0, Pi}]] // HoldForm // TreeForm

This here is what your code does:

That should help you to understand what is going on.

Cheers,

Marco