In mathematics, the Cauchy principal value, named after Augustin Louis Cauchy, is a method for assigning values to certain improper integrals which would otherwise be undefined.In calculus, an improper integral is the limit of a definite integral as an endpoint of the interval of integration approaches either a specified real number or or or, in some cases, as both endpoints approach limits.It is often necessary to use improper integrals in order to compute a value for integrals which may not exist in the conventional sense (as a Riemann integral, for instance) because of a singularity in the function, or an infinite endpoint of the domain of integration.