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AlexKryuchkov
AlexKryuchkov is offline
#10
Mar7-12, 05:30 PM
P: 1
Quote Quote by Muneer QAU View Post
i read that real and imaginary parts of a complex number can be separated by following equation
1/x+iη=P(1/x)-iδ(x)
where P is principal of x i dunt understand this equation can any 1 explain this?????????

the simplest example is if you have
\int \frac{f(x)}{\text{i$\epsilon $}+x} \, dx

so sometimes it is usefull to rewrite it in way
\int \frac{f(x)}{\text{i$\epsilon $}+x} \, dx=P \int \frac{f(x)}{x} \, dx-i \pi f(x)

where P means that you integrate in terms of principal value