Rayleigh probability density function
Y = raylpdf(X,B)
Y = raylpdf(X,B) computes the Rayleigh pdf at each of the values in X using the corresponding scale parameter, B. X and B can be vectors, matrices, or multidimensional arrays that all have the same size, which is also the size of Y. A scalar input for X or B is expanded to a constant array with the same dimensions as the other input.
The Rayleigh pdf is