Convolution with an delta function

Click For Summary
Convolving an arbitrary function f(t) with comb(t), which consists of delta functions at intervals of nT, results in a series of discrete points where f(t) is evaluated at those specific intervals. The convolution effectively samples the function f(t) at each spike of the comb function. The outcome is not an array of copies of f(t) but rather a set of values corresponding to f(nT). The solution hinges on understanding the sampling property of the delta function. Ultimately, the task is to determine the nature of the convolution based on the properties of f(t).
spaghetti3451
Messages
1,311
Reaction score
31

Homework Statement



Convolve an arbitary function f(t) with comb(t) [a sum of delta functions that run from -infinity to infinity with spikes at t = nT]. Is the convolution an array of copies of f(t) or is it a set of discrete points such that f(t) is returned at every t = nT?

Homework Equations





The Attempt at a Solution



The solution depends on the domain of f(t).
 
Physics news on Phys.org
f(t)*\delta(t-t_0) = \int\limits_{-\infty}^{\infty} \delta(\tau-t_0) f(t-\tau) \,d\tau=f(t-t_0)
via sampling property of the impulse
 
So what's the answer?
 
failexam said:
So what's the answer?

That is what *you* are required to figure out.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
1
Views
2K
Replies
1
Views
1K
Replies
2
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 11 ·
Replies
11
Views
7K
  • · Replies 3 ·
Replies
3
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K