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# wlognstat

## PURPOSE

Mean and variance for the Lognormal distribution.

## SYNOPSIS

[m,v]= wlognstat(m0,v0);

## DESCRIPTION

``` WLOGNSTAT Mean and variance for the Lognormal distribution.

CALL:  [m,v] = wlognstat(m0,v0)

m, v = the mean and variance, respectively
m0, v0 = parameters of the Lognormal distribution.

Mean (m) and variance (v) for the Lognormal distribution is

m=exp(m0+v0/2)  and  v=exp(2*m0+v0)*(exp(v0)-1);

Example:
[m,v] = wlognstat(0,1)```

## CROSS-REFERENCE INFORMATION

This function calls:
 comnsize Check if all input arguments are either scalar or of common size. error Display message and abort function. nan Not-a-Number.
This function is called by:
 dist2dcdf Joint 2D CDF computed as int F(X1 dist2dstat Mean and variance for the DIST2D distribution mdist2dstat Mean and variance for the MDIST2D distribution.

## SOURCE CODE

```001 function [m,v]= wlognstat(m0,v0);
002 %WLOGNSTAT Mean and variance for the Lognormal distribution.
003 %
004 % CALL:  [m,v] = wlognstat(m0,v0)
005 %
006 %   m, v = the mean and variance, respectively
007 % m0, v0 = parameters of the Lognormal distribution.
008 %
009 %  Mean (m) and variance (v) for the Lognormal distribution is
010 %
011 %  m=exp(m0+v0/2)  and  v=exp(2*m0+v0)*(exp(v0)-1);
012 %
013 % Example:
014 %   [m,v] = wlognstat(0,1)
015
016 % Reference: Cohen & Whittle, (1988) "Parameter Estimation in Reliability
017 % and Life Span Models", p. 59 ff, Marcel Dekker.
018
019
020
021 % Tested on; Matlab 5.3
022 % History:
023 % revised pab 24.10.2000
024 %  - added comnsize, nargchk
025 %  - added default values
027
028 error(nargchk(0,2,nargin))
029 if nargin<1|isempty(m0),  m0=0;  end
030 if nargin<2|isempty(v0),  v0=1;  end
031
032 [errorcode, m0, v0] = comnsize (m0, v0);
033 if (errorcode > 0)
034   error ('m and v must be of common size or scalar');
035 end
036
037 m = zeros(size(m0));
038 v = m;
039 k = find(v0>=0);
040 if any(k),
041   m(k) = exp(m0(k)+v0(k)/2);
042   v(k) = exp(2*m0(k)+v0(k)).*(exp(v0(k))-1);
043 end
044 k1 = find(v0<0);
045 if any(k1),
046   tmp=NaN;
047   m(k1) = tmp(ones(size(k1)));
048   v(k1) = m(k1);
049 end
050
051
052```

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

Comments or corrections to the WAFO group

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