Convolution of a Cauchy distribution and a uniform distribution

ID: convolution-of-a-cauchy-distribution-and-a-uniform-distribution

Let have the Standard Cauchy distribution and let , independently, have the uniform distribution on , where . The convolution of probability densities gives the probability density of as
This is an even function. Its derivative is
so its unique mode is zero. Its tails satisfy as : multiplying the integral by makes the integrand converge uniformly to on the bounded interval . Consequently both positive and negative parts of the first moment diverge, so its expected value does not exist. The symmetric Cauchy principal value of that moment is zero, which is a different assertion. Adding a bounded independent displacement smooths the probability density without removing the divergent first moment of the Cauchy distribution.

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