You could chain the return value of an assignment e.g

$min[$i] = $max[$i] = $emax[$i] = $len;
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Or you could just repeat the value e.g

($min[$i], $max[$i], $emax[$i]) = ($len) x 3;
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Update: or as merlyn might have it

$_ = $len for $min[$i], $max[$i], $emax[$i];
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See. perlop and perlsyn for more info.