Spread Calculation Theorem of Improper Integral Cauchy Principal Value in Complex Functions

This article discusses the use of the theorem of the residues to calculate Cauchy's Principal values of the improper integral, where auxiliary function has poles of higher order on the real axis and proposes a new theorem of culcuation. Applying this new theorem, one can easily find the auxiliary function and solve many problems of Cauchy's principal values of improper integral as well, the original theorem being unable to do so.