# Toronto Math Forum

## APM346-2012 => APM346 Math => Misc Math => Topic started by: Kun Guo on November 10, 2012, 05:33:03 PM

Title: Lec 23 Possion formula clarification
Post by: Kun Guo on November 10, 2012, 05:33:03 PM
Attached picture is a screen shot of online notes lecture 23. I was wondering if there is an addition r in front of sin(n*theta) in (12). Also, is there missing a^(-n) in calculating An and Cn?
Title: Re: Lec 23 Possion formula clarification
Post by: Victor Ivrii on November 10, 2012, 05:43:06 PM
Good catch
Title: Re: Lec 23 Possion formula clarification
Post by: Miranda Jarvis on November 18, 2012, 03:14:20 PM
I don't understand, if in equation (12) we are plugging in r=a to eq(10) how is there still and r involved as a variable?
Title: Re: Lec 23 Possion formula clarification
Post by: Victor Ivrii on November 18, 2012, 03:26:52 PM
I don't understand, if in equation (12) we are plugging in r=a to eq(10) how is there still and r involved as a variable?

We plug $r=a$ to recover coefficients (which do not depend on $r$). After they are recovered we plug them to the original expression for $u$ which  still contains $r$.
Title: Re: Lec 23 Possion formula clarification
Post by: Aida Razi on December 08, 2012, 01:10:03 PM
I was wondering if Cn has to be sin(nÎ¸) instead of cos(nÎ¸)?
Title: Re: Lec 23 Possion formula clarification
Post by: Victor Ivrii on December 08, 2012, 02:49:18 PM
I was wondering if Cn has to be sin(nÎ¸) instead of cos(nÎ¸)?

Yes, corrected.