Hi I am using metrop in MCMC library.  Since some times the prior density is 0
and
the log prior density would be –Inf, I ask the return value for loglikelihood
equal to Min.log, which is defined as log(.Machine$double.xmin)-400, whenever a
–Inf occurs to the logdensity.  However,
I noticed if two Min.log’s happen in a row, the sampled parameter value for the
second Min.log is treated as accepted. 
As a result, the parameters result in 0 prior density are included in my
results, which I do not want to do.  How
should I deal with it to avoid the acceptance of these iterations in MCMC? 
Thanks for your help!
      
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