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wchi2inv

PURPOSE ^

Inverse of the Chi squared distribution function

SYNOPSIS ^

x = wchi2inv(F,p)

DESCRIPTION ^

 WCHI2INV Inverse of the Chi squared distribution function 
  
  CALL:  x = wchi2inv(F,p) 
  
         x = inverse cdf for the Chi squared distribution evaluated at F 
         p = degrees of freedom 
  
  
  Example: 
      F = linspace(0,1,100); 
      x = wchi2inv(F,1); 
      plot(F,x)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

001 function x = wchi2inv(F,p) 
002 %WCHI2INV Inverse of the Chi squared distribution function 
003 % 
004 % CALL:  x = wchi2inv(F,p) 
005 % 
006 %        x = inverse cdf for the Chi squared distribution evaluated at F 
007 %        p = degrees of freedom 
008 % 
009 % 
010 % Example: 
011 %     F = linspace(0,1,100); 
012 %     x = wchi2inv(F,1); 
013 %     plot(F,x) 
014  
015 % Reference: Johnson, Kotz and Balakrishnan (1994) 
016 % "Continuous Univariate Distributions, vol. 1", p. 415 ff 
017 % Wiley 
018  
019 % Tested on; Matlab 5.3 
020 % History:  
021 % revised pab 25.10.2000 
022 %  - added comnsize, nargchk 
023 % added ms 26.06.2000 
024 error(nargchk(2,2,nargin)) 
025  
026 if any(p~=round(p)), 
027   warning('p should be an integer') 
028 end 
029 [errorcode,F,p2,b] = comnsize(F,p/2,2); 
030 if errorcode > 0 
031   error('F and p must be of common size or scalar.'); 
032 end 
033  
034 x=wgaminv(F,p/2,2); 
035

Mathematical Statistics
Centre for Mathematical Sciences
Lund University with Lund Institute of Technology

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