• Support PF! Buy your school textbooks, materials and every day products Here!

Better integration strategy?

  • Thread starter dvchench
  • Start date
  • #1
17
0
I'm doing a HW problem that involved trying to find Fourier series. I know how to do it, but I'm really bothered by the fact that I have to do so much trigonometric integration by parts. my question is, is there any better way to solve the problem:

<int,indef.,dt>{ sin(a*t)*cos(b*t) } or is the only way to chug along with the two messy layers of integration by parts?

also, it seems like i'm missing something: how do you write pretty-print equations in posts?

edit: i should add, that the problem is asking for a fourier series for a half-wave rectified sine, but that isn't vital to the question
 

Answers and Replies

  • #2
gabbagabbahey
Homework Helper
Gold Member
5,002
6
I'm doing a HW problem that involved trying to find Fourier series. I know how to do it, but I'm really bothered by the fact that I have to do so much trigonometric integration by parts. my question is, is there any better way to solve the problem:

<int,indef.,dt>{ sin(a*t)*cos(b*t) } or is the only way to chug along with the two messy layers of integration by parts?
Why are you concerned with the indefinite integral? Usually one integrates over a half-period interval in order to take advantage of the orthogonality of sine and cosine.

also, it seems like i'm missing something: how do you write pretty-print equations in posts?
See my signature.
 
  • #3
17
0
gabbagabbahey,
thanks for the reply. I'm only concerned because it seems like I'm doing it the hard way - after 1.5 pages of math, I'm starting to feel like I'm mowing the lawn with a pair of nail clippers (or mopping a gym floor with a toothbrush, take your pick of metaphor). I just wanted to make sure that by parts is the only reasonable way of doing it and I'm not missing any good shortcut.
 

Related Threads on Better integration strategy?

  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
1K
Replies
2
Views
2K
Replies
3
Views
5K
  • Last Post
Replies
0
Views
862
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
3
Views
2K
Replies
3
Views
2K
Top