WCHI2STAT Mean and variance for the Chi squared distribution. CALL: [m,v] = wchi2stat(p) m, v = the mean and variance, respectively p = degrees of freedom, p=1,2,3,.... Mean (m) and variance (v) for the Chi squared distribution is m=p and v=2p; Example: [m,v] = wchi2stat(2)
001 function [m,v]= wchi2stat(p); 002 %WCHI2STAT Mean and variance for the Chi squared distribution. 003 % 004 % CALL: [m,v] = wchi2stat(p) 005 % 006 % m, v = the mean and variance, respectively 007 % p = degrees of freedom, p=1,2,3,.... 008 % 009 % Mean (m) and variance (v) for the Chi squared distribution is 010 % 011 % m=p and v=2p; 012 % 013 % Example: 014 % [m,v] = wchi2stat(2) 015 016 % Reference: Johnson, Kotz and Balakrishnan (1994) 017 % "Continuous Univariate Distributions, vol. 1", p. 415 ff 018 % Wiley 019 020 % Tested on; Matlab 5.3 021 % History: 022 % revised pab 25.10.2000 023 % - found a bug: forgot multiplication 024 % - added warning+nan's 025 % added ms 26.06.2000 026 027 m = p; 028 v = 2*p; 029 ok = find(p~=round(p) & p>0); 030 if any(~ok), 031 warning('p should be a positive integer') 032 m(k)=NaN; 033 v(k)=NaN; 034 end 035 036 037 038
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