help for MLE

Hi,
when I write the likelihood function as
fn<-function(x) -50*log(2*pi)-100*log(sigma)-(1/2*(sum((x-mu)/sigma)^2))
then what should I do since it shows that Error in log(sigma) : Object 
"sigma" not found.

Thanks
edward

From: Edward Sun

Dear Sir/Madam,

I am using R version 1.8.1. I am doing following tast:

First generate 100 Gaussion(3,1) numbers, then write the
likelihood function
to estimate the parameters of Gaussian distribution by direct
maximizing the
likelihood function.

My likelihood function is:
fn<-function(x)
(-50*log((sd(x))^2))-50*log(sqrt(2*pi))-(1/2*((mean(x))^2))*(
sum((x-(mean(x))^2))

After I input above function, the '' >'' turned to be '' +
''. and it did
not work.

I am looking for the help to solve this tast by writting a likelihood
function.

Thanks a lot.

Best regards.
edward sun

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Edward  -

Either  optim()  or  fitdistr()  has an additional required
argument which specifies the names (and incidentally starting
values) for the parameters to be estimated.  Did you supply
that argument ?  See  help("optim"), help("fitdistr").

-  tom blackwell  -  u michigan medical school  -  ann arbor  -

Hi,
when I write the likelihood function as

fn<-function(x) -50*log(2*pi)-100*log(sigma)-(1/2*(sum((x-mu)/sigma)^2))
then what should I do since it shows that Error in log(sigma) : Object
"sigma" not found.

Thanks
edward

From: Edward Sun

Dear Sir/Madam,

I am using R version 1.8.1. I am doing following tast:

First generate 100 Gaussion(3,1) numbers, then write the
likelihood function
to estimate the parameters of Gaussian distribution by direct
maximizing the
likelihood function.

My likelihood function is:
fn<-function(x)
(-50*log((sd(x))^2))-50*log(sqrt(2*pi))-(1/2*((mean(x))^2))*(
sum((x-(mean(x))^2))

After I input above function, the '' >'' turned to be '' +
''. and it did
not work.

I am looking for the help to solve this tast by writting a likelihood
function.

Thanks a lot.

Best regards.
edward sun

------------------------------------------------------------------------------
Notice:  This e-mail message, together with any attachments, contains
information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New
Jersey, USA 08889), and/or its affiliates (which may be known outside the
United States as Merck Frosst, Merck Sharp & Dohme or MSD and in Japan as
Banyu) that may be confidential, proprietary copyrighted and/or legally
privileged. It is intended solely for the use of the individual or entity
named on this message.  If you are not the intended recipient, and have
received this message in error, please notify us immediately by reply
e-mail
and then delete it from your system.
------------------------------------------------------------------------------

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

Have you worked through the "posting guide" at the end of each 
r-help email?  In particular, have you worked the examples in 
"help('fitdistr')" in library MASS and "optim"? 

      hope this helps.  spencer graves

Hi,
when I write the likelihood function as

fn<-function(x) -50*log(2*pi)-100*log(sigma)-(1/2*(sum((x-mu)/sigma)^2))

then what should I do since it shows that Error in log(sigma) : Object 
"sigma" not found.

Thanks
edward

From: Edward Sun

Dear Sir/Madam,

I am using R version 1.8.1. I am doing following tast:

First generate 100 Gaussion(3,1) numbers, then write the
likelihood function
to estimate the parameters of Gaussian distribution by direct
maximizing the
likelihood function.

My likelihood function is:
fn<-function(x)
(-50*log((sd(x))^2))-50*log(sqrt(2*pi))-(1/2*((mean(x))^2))*(
sum((x-(mean(x))^2))

After I input above function, the '' >'' turned to be '' +
''. and it did
not work.

I am looking for the help to solve this tast by writting a likelihood
function.

Thanks a lot.

Best regards.
edward sun

------------------------------------------------------------------------------ 

Notice:  This e-mail message, together with any attachments, contains
information of Merck & Co., Inc. (One Merck Drive, Whitehouse 
Station, New
Jersey, USA 08889), and/or its affiliates (which may be known outside 
the
United States as Merck Frosst, Merck Sharp & Dohme or MSD and in 
Japan as
Banyu) that may be confidential, proprietary copyrighted and/or legally
privileged. It is intended solely for the use of the individual or 
entity
named on this message.  If you are not the intended recipient, and have
received this message in error, please notify us immediately by reply 
e-mail
and then delete it from your system.
------------------------------------------------------------------------------ 

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! 
http://www.R-project.org/posting-guide.html