Quote by Muneer QAU
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} \, dxi \pi f(x)
where P means that you integrate in terms of principal value