e/Principal part

Information
has gloss	eng: In mathematics, the principal part has several independent meanings, but usually refers to the negative-power portion of the Laurent series of a function. Laurent series definition The principal part at z=a of a function : f(z) = \sum_k=-\infty}^\infty a_k (z-a)^k is the portion of the Laurent series consisting of terms with negative degree. That is, : \sum_k=-\infty}^-1} a_k (z-a)^k is the the principal part of f at a . If f(z) has an essential singularity at a, then the principal part is an infinite sum, and vice versa.
lexicalization	eng: principal part
instance of	c/Generalized functions