function pdf = quasigeometric_pdf ( x, a, b ) %*****************************************************************************80 % %% QUASIGEOMETRIC_PDF evaluates the Quasigeometric PDF. % % Discussion: % % PDF(A,B;X) = A if 0 = X; % = (1-A) * (1-B) * B^(X-1) if 1 <= X. % % Licensing: % % This code is distributed under the GNU LGPL license. % % Modified: % % 29 January 2009 % % Author: % % John Burkardt % % Reference: % % Darren Glass, Philip Lowry, % Quasiquasigeometric Distributions and Extra Inning Baseball Games, % Mathematics Magazine, % Volume 81, Number 2, April 2008, pages 127-137. % % Paul Nahin, % Digital Dice: Computational Solutions to Practical Probability Problems, % Princeton University Press, 2008, % ISBN13: 978-0-691-12698-2, % LC: QA273.25.N34. % % Parameters: % % Input, integer X, the independent variable. % 0 <= X % % Input, real A, the probability of 0 successes. % 0.0 <= A <= 1.0. % % Input, real B, the depreciation constant. % 0.0 <= B < 1.0. % % Output, real PDF, the value of the PDF. % if ( x < 0 ) pdf = 0.0; elseif ( x == 0 ) pdf = a; elseif ( b == 0.0 ) if ( x == 1 ) pdf = 1.0; else pdf = 0.0; end else pdf = ( 1.0 - a ) * ( 1.0 - b ) * b^( x - 1 ); end return end