why Mathematica 10 does not compute this integral?

Questions
,
1

math_int.png
math_int.png2067Ɨ461 7.97 KB

Why does Mathematica 10 not compute the first one, but compute the second one? Please try the attached file. Thank you.

2

The integration you are trying to compute will not give you any answer because the constant ā€˜sigma vā€™ has a subscript v which is considered as a variable v which runs from (-) Infinity to (+) Infinity. As Mathematica does not know that it is a subscript or a notation,it can not compute. That is why it is convenient to use another symbol say, ā€˜aā€™ instead of ā€˜sigma vā€™.

Integrate[Exp[(-v^2/a^2)/2]/(Sqrt[2 Pi] a), {v, -Infinity, Infinity}]

Perhaps this will work. See the attachment.

3

Hello
Because v appears as the integration variable as a subscript. Try

Integrate[E^(1/2 (-(v^2/
!\*SubsuperscriptBox[\(\[Sigma], vvvv, 2]))))/
Sqrt[2 [Pi]] , {v, -Infinity, Infinity}]

For some reason the ā€œcode block <>ā€ is not appearing on this community editor. Sorry, cut and paste should work. Adding an image even though this is ā€œbad practiceā€

6339Untitled.png
6339Untitled.png772Ɨ324 16.3 KB

4

Sorry Suvadip,
You had answered while I was creating a response.

5

Thank you very much! That explains.

6

Hi Craig,

Please do not mind.

sincerely, Suvadip.

7

The code block ikon moved left in the edit row.

comm420720.jpg

8

Thanks.
Palm slap to foreheadā€¦
I saw that it had moved the following day. I would have never survived in the wild.

I am wondering if that icon needs some words above or beside it, such as ā€œUse this for Posting Codeā€? I donā€™t find <> is obvious for its purpose.

9

I didnā€™t find it obvious either. While I prefer the new location, it took me a bit to figure out what had changed (and thus why my code sections did not format correctly).