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Cauchy's law

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Definition

Definition

Let c>0c > 0. XX follows the Cauchy's law with the parameter cc if its density is :

fX(x)=1πcc2+x2.f_X(x) = \frac{1}{\pi}\frac{c}{c^2+x^2}.

We note XC(c)X \sim \mathcal{C}(c).

Results

Proposition : Cauchy law's characteristic function

Let XX be a random variable. If XC(c)X \sim \mathcal C(c), the characteristic function of XX is

ϕX(t)=ect.\phi_X(t) =e^{-c|t|}.