The probability density of random variable ξ obeying Laplacian distribution is φ (x) = AE ^ f (x) = Ke ^ - | x | and the coefficient a is obtained,

The probability density of random variable ξ obeying Laplacian distribution is φ (x) = AE ^ f (x) = Ke ^ - | x | and the coefficient a is obtained,

That is to say, in the positive half axis φ (x) = Ke ^ (- x) (X & gt; 0) and in the negative half axis φ (x) = Ke ^ x (X & lt; 0), they are exponential functions, and they are symmetric about the Y axis. Finding a can integrate the function. Because of symmetry, the integrals on both sides should be equal, and the sum is 1, so one side is 1 / 2, and Ke ^ (- x) can get k = 1 / 2 by integrating (0 to positive infinity)