- #1
md5fungi
- 24
- 0
Homework Statement
[tex]\int_{-\infty}^t (cos \tau)\delta(\tau) d\tau[/tex]
Evaluate the integral. I'm supposed to evaluate this for all t I believe, so I'm concerned with t<0, t=0, t>0.
Homework Equations
[tex]\int_{-\infty}^{\infty} f(x)\delta(x) dx = f(0)[/tex]
The Attempt at a Solution
I understand the second equation will give me some of my answer. When t is infinity, cos 0 is to be evaluated, and I get 1. The problem is, I don't really understand how the Dirac Delta function works with integrals. I have no idea what would happen if I let t = -5, or t = 0, with merely the one equation I am given. The textbook I am using doesn't seem to give much information besides the above equation, and how the Delta function and Unit Step function relate.
Can anyone help me understand this better?
The answer is given to me, as well: 1 for t > 0, 0 for t < 0, not defined for t = 0.