From: Peter Zotov <whitequark@...>
Date: 2009-04-08T22:31:59+09:00
Subject: Re: what is happening here

Quoting George George <george.githinji@gmail.com>:

> i have some perl code
>
> while ($high - $low > 0.001) {    # precision
>     # calculate the sum of all normalized scores
>     my $sum = Pn * Pn * exp($lambda * $match)    * 4
>             + Pn * Pn * exp($lambda * $mismatch) * 12;
>     # refine guess at lambda
>     if ($sum > 1) {
>         $high = $lambda;
>         $lambda = ($lambda + $low)/2;
>     }
>     else {
>         $low = $lambda;
>         $lambda = ($lambda + $high)/2;
>     }
> }
>

Pn * exp($lambda * $match) is Pn * (Math::E ** (lambda + match)), not  
Pn ** (lambda + match).

   WBR, Peter Zotov