Syntax error to generate Log Normal Variables
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I would like to generate 2x4 matrix of values which are log normally distributed
with mu= 1.175 and sigma = 0.0768 .. However when I write the following command
A= lognrnd(1.175,0.0768,2,4);
It appears the ouput error as follows:
??? Undefined function or method 'lognrnd' for input arguments of type 'double'.
Can any person please help me to resolve the issue ?
2 个评论
Star Strider
2012-9-12
It is a Statistics Toolbox function.
Type:
which lognrnd -all
on the Command Line to see if it exists on your system, and to be sure there is only one function with that name.
Jav Neo
2012-9-13
采纳的回答
Use this instead:
A = exp(randn(2,4).*0.0768+1.175)
Or make a little function:
Lognrand = @(S,mu,sig) exp(randn(S).*sig+mu);
A = Lognrand([2,4],1.175,0.0768);
To check:
m = 5/3;
v = 7/5;
mu = log((m^2)/sqrt(v+m^2));
sigma = sqrt(log(v/(m^2)+1));
A = Lognrand([1,1e7],mu,sigma);
abs(mean(A)-m)/m % Should be pretty small
abs(var(A)-v)/v
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