Erasures decoding of Reed Solomon codes

On Tue, 24 May 2016 12:14:12 -0500, Tim Wescott
<seemywebsite@myfooter.really> wrote:

>On Mon, 23 May 2016 12:46:22 -0500, Tim Wescott wrote:
>
>> On Sat, 21 May 2016 14:55:38 -0700, kortas.manel wrote:
>> 
>>> Le mercredi 31 ao&ucirc;t 2005 20:35:16 UTC+1, Mike McLernon a &eacute;crit&nbsp;:
>>>> Hi,
>>>> 
>>>> I'm building an erasures decoder for Reed Solomon codes, and I'm
>>>> having trouble when the number of erasures (without errors) exceeds
>>>> (n-k)/2, the error-correcting capability of the code.  When my code
>>>> has no errors, and only erasures, I would expect the error locator
>>>> polynomial to be uniquely 1.
>>>> When I have up to (n-k)/2 erasures, that's exactly what happens.
>>>> However, when the number of erasures exceeds (n-k)/2, my error locator
>>>> polynomial exhibits unusual behavior.  I run into the following
>>>> circumstances in these cases:
>>>> 
>>>> 1)    the polynomial has no roots in the field of the code, or 2)
>>>> the polynomial has repeated roots, or 3)    the polynomial's roots are
>>>> a subset of the erasure locations, or 4)    the polynomial's roots are
>>>> different from the erasure locations.
>>>> 
>>>> Scenarios 1-3 seem reasonable, in that I can discard the information
>>>> in the error locator polynomial.  I already have that information from
>>>> the erasure locator polynomial.  However, scenario 4 is troublesome,
>>>> and I'm not quite sure how to handle that one.
>>>> 
>>>> Any help would be appreciated.
>>>> 
>>>> Mike McLernon
>>> can any one provide me the source code of reed solomon in matlab with
>>> BM or euclidien or PGZ method please? thx in advance
>> 
>> Not for free, generally, and not if you're a student, ever.  We and you
>> both benefit from you doing your own homework.  If you can't do your own
>> homework -- switch majors.
>
>Boy, that was harsh.  And I forgot the rider: we're pretty much 
>universally opposed to _doing_ your homework for you, but there's quite a 
>bit of us (myself included) who are delighted to _help_ you to understand 
>your homework so that you might do it yourself.
>
>We _won't_ help to raise up a generation of ignorant engineers who spend 
>a minimal amount of time screwing things up before becoming managers and 
>_really_ screwing things up.  But we're happy to help raise up the next 
>generation of _competent_ engineers.

That's about as well as I've seen that put for a while.