prime gaps

#!/usr/bin/env perl
use warnings;
use strict;
use Math::BigFloat lib=>"GMP";
use Math::GMPz;
use Math::Prime::Util qw/:all/;
use feature ':5.10';
use File::Slurp;

my $prim=47;
my @crt = (2552748177891450,4525099353657960,4890645049862880,6157389981878520,10854052306322600,8195665938985140,16650825898473700);

my $beg = shift || 1;
my $end = shift || 3000000000;
my $fact = Math::GMPz->new(primorial($prim));
my $minustarget = 200;
my $target=150;
my $filename='primegaps-perl.txt';
my $addi=0;
my $line="";
my $meritrec=0;
my $gaprec=0;

my $counter=-1;

foreach my $i ($beg .. $end)
{

    $counter=$counter+1;
    if ($counter == 50000) {
        print "$i\n";
        $counter=0;
    }
    my $fact_i = $fact * $i;



    foreach my $a (@crt)
    {
        my $num = $fact_i+$a+855;
            my $start = prev_prime($num);
        my $startpoint = $num-$start;

        if ($startpoint> $minustarget)
        {
            my $end = next_prime($num);
                my $gap = $end - $start;
            my $endpoint = $end-$num;

            if ($gap> $target)
            {

                open(my $fh, '>>', $filename) or die "Could not open file '$filename' $!";
                my $merit = merit($start, $gap);

                 if ($merit <15 && $gap>$target) { $target=$gap; print "nouvel écart : $target\n";}
                    print "$i  $a  $startpoint $endpoint $gap  $merit\n";
                    my $addi=$a+855;
                    if ($merit > $meritrec || $merit > 21.5 ){
                        $meritrec=$merit ; say "nouveau record de merite : $meritrec";
                        $line= "$i*$prim#+$addi-$startpoint et l'ecart est de $gap et a un merite de $merit";
                        say $fh "$line";
                    }
                    if ($gap > $gaprec) {
                        $gaprec=$gap; say "nouveau record d 'ecart : $gaprec";

                    }
                    else {

                        $line= "$i*$prim#+$addi-$startpoint et l'ecart est de $gap";
                    }
                    print "$line\n";
                    close $fh;
            #} else {
            #   print "merite pas assez gros\n";
            #   }
            }

        }
    }

}

sub merit {
 my($n, $gap) = @_;
 my $fgap = Math::BigFloat->new("$gap");
 my $fn   = Math::BigFloat->new("$n");
 return sprintf("%.6lf", $fgap / log($fn));
}