i solved the problem using this: 
LINE: for (my $i=0; $i<20; $i++){
    for (my $j=0; $j<20; $j++){
        if ($matrix[$i][$j] =~ /[^0.00]/){
            $lnpam[$i][$j] = log $matrix[$i][$j];
        }else{ next LINE;
        }
    }
}

[download]
thanks a lot for the quick answer!

In reply to Re^2: Calculate log of matrix values by madM
in thread Calculate log of matrix values by madM

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