Horner rule for evaluating a polynomial from an array of coefficients: 

sub bytearray_to_bigint {
    my $result = Math::BigInt->new('0');
    while (@_) {
        $result <<= 8; # was *= 256;
        $result += pop;
    }
    $result;
}

[download]
This algorithm is pretty efficient and needs no data tables kept.

After Compline,
Zaxo

In reply to Horner Rule Re: Converting an array of bytes into a BigInt by Zaxo
in thread Converting an array of bytes into a BigInt - speed considerations by dempa

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