[R] my code in Metro_Hastings

[hms Dreams]

Hi again :)
my code is in the attachment file
the problem I think in the :



mcmc_r=Metro_Hastings(li_func=baysianlog, pars=c(1,1,1),par_names=c('alpha','gamma','delta'),data=x
)


because  I did not write the prop_sigma because I don't know how can I calcalute the covariance matrix.
 
somebody told me to compute the cov without itreation then  add the reasulting cov matrix to metro hasting using itreation
but it also gave me  an error 
 
Can you check my code and correct it please �� 
 
Thank you,
Sara