Hi,
Thanks; I have changed initialization values of parameters and now its
working fine , also i run your script its also gving perfect results.
Thank you very much
Bye
Haider
On 10 May 2010 18:15, Allin Cottrell <cottrell(a)wfu.edu> wrote:
 On Mon, 10 May 2010, Allin Cottrell wrote:
 > On Mon, 10 May 2010, RAZIA HAIDER wrote:
 >
 > > Thanks for quick reply. First i realized my basic mistakes :), now i
 have
 > > changed script, which is given below...
 By the way, if you want to use analytical derivatives, which may
 give better convergence, here's a version that does that:
 <script>
 open data7-9
 series y = vsat
 scalar a = -0.5 * log(sqrt(2*pi))
 # your initialization here...
 scalar mu = 400
 scalar sigma = 100
 mle logl = a - log(sigma) - (y-mu)^2 / (2*sigma^2)
  deriv mu = (y-mu) / (2*sigma^2)
  deriv sigma = -1/sigma + (y-mu)^2 / (sigma^3)
 end mle
 # check results
 scalar n = $nobs
 scalar sigma_hat = sqrt(var(y) * (n-1)/n)
 printf "mean = %g, sigma_hat = %g\n", mean(y), sigma_hat
 </script>
 Allin Cottrell
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-- 
Razia Haider
Ph.D. student
Dipartimento di Ingegneria dell'Informazione
Universita' di Modena e Reggio Emilia
Via Vignolese 905, 41100 Modena, Italy
e-mail: razia.haider(a)unimo.it
tel: +39 059 2056314