MATERNFUN Returns the Matern function. MATERNFUN is a low-level function called by MATERNCOV. M=MATERNFUN(ALPHA,X) returns the value of the Matern function of order ALPHA at location X, with ALPHA>1/2. The Matern function is defined as M(X)=C*|X|^(ALPHA-1/2) K_(ALPHA-1/2)(|X|) where K_ALPHA is the modified Bessel function of the second kind of order ALPHA, and C=2/GAMMA(ALPHA-1/2)./2^(ALPHA-1/2) is a normalizing constant. This definition implies M(0)=1. For the special case of ALPHA=1/2, the GAMMA function in C is omitted in order to avoid developing a singularity. This change is acceptable because this function is used only in ratios for ALPHA<=1/2. 'maternfun --f' generates a sample figure. Usage: M=maternfun(alpha,x); __________________________________________________________________ This is part of JLAB --- type 'help jlab' for more information (C) 2013--2017 J.M. Lilly --- type 'help jlab_license' for details