mrbayes, Sumt ; Error when setting parameter "Filename" (1) question 1
I wanted to use sumt command after completion of mcmc run. Whenever I use, sumt Filename=infile.nex, it gives me the error:
A matrix must be specified before sumt can be used
Error when setting parameter &quot;Filename&quot; (1) 

But for the same analysis, I can use sump without any problem. What should I do now?
question 2
Another issue, I used burn in as 25% where as in Tracer, it is always showing 10%. No matter how much burn in I use, Tracer always shows 10% as burn in.
system stats
Operating system : Centos7
Version of MrBayes: 3.2.6

Thanks in advance,
Best Regards,
Zillur
Having thought this through, I think you've made a mistake. The file it wants is the outfile, you have given it the infile only. My original answer is below.

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From memory (my personal memory, not RAM, SSD or Stata), in the run command, you need to specify,

nruns=2


sumt will then combine both runs. If the file name is mystuff.run and nruns=2, there will be an output of mystuff.run1.t and mystuff.run2.t.

If nruns isn't set then sumt will not work, or if the MCMCMC output ends up with different names again sumt will not work.

With the burnin, you simply specify this in MrBayes. It is easy to write a script that will perform a 25% burnin. Tracer is nicely written, presumably C, its fast, but it has been around for a long time.