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wraylcdf

PURPOSE ^

Rayleigh cumulative distribution function

SYNOPSIS ^

F = wraylcdf(x,b);

DESCRIPTION ^

 WRAYLCDF Rayleigh cumulative distribution function
 
  CALL:  F = wraylcdf(x,b);
 
         F = distribution function evaluated at x
         b = parameter
  
  The Rayleigh distribution is defined by its cdf
 
   F(x;b) = 1 - exp(-x^2/(2b^2)), x>=0
 
  Example: 
    x = linspace(0,4,200);
    p1 = wraylcdf(x,1); p2 = wraylcdf(x,0.5);
    plot(x,p1,x,p2)

CROSS-REFERENCE INFORMATION ^

This function calls: This function is called by:

SOURCE CODE ^

001 function F = wraylcdf(x,b);
002 %WRAYLCDF Rayleigh cumulative distribution function
003 %
004 % CALL:  F = wraylcdf(x,b);
005 %
006 %        F = distribution function evaluated at x
007 %        b = parameter
008 % 
009 % The Rayleigh distribution is defined by its cdf
010 %
011 %  F(x;b) = 1 - exp(-x^2/(2b^2)), x>=0
012 %
013 % Example: 
014 %   x = linspace(0,4,200);
015 %   p1 = wraylcdf(x,1); p2 = wraylcdf(x,0.5);
016 %   plot(x,p1,x,p2)
017 
018 % Reference: Cohen & Whittle, (1988) "Parameter Estimation in Reliability
019 % and Life Span Models", p. 181 ff, Marcel Dekker.
020 
021 
022 % Tested on; Matlab 5.3
023 % History:
024 % revised pab 24.10.2000
025 %  - added comnsize, nargchk
026 % added ms 15.06.2000
027 
028 error(nargchk(2,2,nargin))
029 [errorcode, x, b] = comnsize (x,b);
030 if (errorcode > 0)
031   error ('x and b must be of common size or scalar');
032 end
033 
034 F=zeros(size(x));
035 
036 k = find ((x>=0)&(b>0));
037 if any (k)  
038   F(k)=1-exp(-x(k).^2./(2*b(k).^2));
039 end
040 
041 k1 = find (b<=0);
042 if any (k1)
043   tmp=NaN;
044   F(k1) = tmp(ones(size(k1)));
045 end
046 
047 
048 
049 
050

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

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