Asuming IEEE double-precision floating-point numbers on your platform, you can use this horrid idea (: 

BEGIN {
    my $code= "";
    if(  pack("L",1) ne pack("N",1)  ) {
        $code= "''.reverse ";
    }
    eval "sub to_big_endian { ${code}pop }; 1"
        or die $@;
}
sub to_bin {
    my( $num )= @_;
    my( $sign, $exp, $mant )= unpack "A1A11A*", unpack "B*",
        to_big_endian pack"d",2*$num+1;
    $mant =~ s/10*$//;
    return "1".$mant;
}

[download]
That should work to about 52 bits for positive integers on compatible platforms.

Don't put this in production code! :)

        - tye (but my friends call me "Tye")

In reply to (tye)Re: dec to bin conversion for large numbers by tye
in thread dec to bin conversion for large numbers by Anonymous Monk

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