Homework Statement
Hi everyone. I am trying to calculate $$f(k) = \int_{-\infty}^0 e^{-i k t} dt.$$
Homework Equations
Of course we know that $$\int_{-\infty}^{\infty} e^{-i k t} dt = 2 \pi \delta(k)$$ and in fact (I think) I know that the answer to my question must be $$f(k) = \frac{i}{k}...