# [Math] Understanding Dirac Delta

dirac deltaintegration

I found this:

What the author wants you to think is that $f(\infty)H(\infty)- f(-\infty)H(-\infty) = 0\cdot 1 - f(-\infty)\cdot 0 = 0-0 = 0$ and $H=0$ on $(-\infty,0)$ so the integral from $-\infty$ to $\infty$ can be replaced by an integral from $0$ to $\infty$.