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Generation of Random Variates

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Generation of Random Variates

by

James Huntley (view profile)

 

generates random variates from over 870 univariate distributions

asymsub_pdf(x, alpha, kappa, sigma, theta)
% asymsub_pdf.m - evaluates an Asymmetric Subbotin Probability Density.
%   See "Macroeconomic Fluctuations and the Firms' Rate of Growth Distribution:
%   Evidence from US and UK Quoted Companies," E. Santoro, Cambridge, Oct., 2006.
%
%   Vector form of PDF!!!
%
%  Created by Jim Huntley,  7/6/07
%

function [pdf] = asymsub_pdf(x, alpha, kappa, sigma, theta)

%persistent ka sa coef 

%if(isempty(coef))
    ka = kappa^alpha;
    sa = sigma^alpha;
    coef = exp(log(alpha*kappa) -(gammaln(1/alpha)+log(sigma)+log(1+kappa^2)));
%end

for jx = 1:size(x,2)
    if(x(jx) < theta)
        pdf(jx) = exp(-abs(x(jx)-theta)^alpha/(sa*ka)) * coef;
    elseif(x(jx) >= theta)
        pdf(jx) = exp(-(x(jx)-theta)^alpha*ka/sa) * coef;
    end
end

return

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