Thanks!!!! It works fine now and, as you said, substantially faster also. This is what I did, 
foreach my $pair (@lpairs) {
    my $n = 0;
    my $z = 0;
    my $hl;
    my $pvalue = 0;
    my $pvt = 0;
    my $fk;
    foreach $fk (%ipairs) {
        if( exists $ipairs{$fk} &&  exists $ipairs{$fk}{$pair} &&  exi
+sts $ipairs{$fk}{$pair}{'pvalue'}){
        #if($ipairs{$fk}{$pair}{'pvalue'}){
            $pvt = $ipairs{$fk}{$pair}{'pvalue'};
            if($pvt){
                unless($hl){
                    $hl = $ipairs{$fk}{$pair}{'head'};
                }
                $n++;
                $z+= qnorm($ipairs{$fk}{$pair}{'pvalue'});
            }
        }
    }
    if($n>2){
        $z = $z/sqrt($n);
        $pvalue = pnorm($z);
    }    
    if ($pvalue) {
        #printf "$pair -> %.4f\n", $pvalue; 
        printf OF "$hl %.4f $n\n", $pvalue;
    }

}

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In reply to Re^2: memory issues by asqwerty
in thread memory issues by asqwerty

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