FP array checksum?

[larry@portcommodore.com]

I would like to generate a checksum for a small array of floating
point numbers (to see if there was a change in or not in the array,
without having to have all the original values in a form.) some sort
of CRC would be nice.

Any know of any sample code or suggestions?

[Gordon]

Re: FP array checksum?

On Aug 7, 7:10 pm, la...@portcommo dore.com wrote:

I would like to generate a checksum for a small array of floating
point numbers (to see if there was a change in  or not in the array,
without having to have all the original values in a form.) some sort
of  CRC would be nice.
>
Any know of any sample code or suggestions?

$checksum = crc32 (implode ($myArray));

[larry@portcommodore.com]

Re: FP array checksum?

On Aug 7, 1:11 pm, Gordon <gordon.mc...@n tlworld.comwrot e:

Any know of any sample code or suggestions?

>
$checksum = crc32 (implode ($myArray));

Darn you! It had to be so easy.. :-)

Thanks.

[=?iso-8859-1?Q?=C1lvaro?= G. Vicario]

Re: FP array checksum?

*** larry@portcommo dore.com escribió/wrote (Thu, 7 Aug 2008 11:10:08 -0700
(PDT)):

I would like to generate a checksum for a small array of floating
point numbers (to see if there was a change in or not in the array,
without having to have all the original values in a form.) some sort
of CRC would be nice.
>
Any know of any sample code or suggestions?

You can use serialize() on the array to get a string and then apply a
hashing function like md5(), sha1() or crc32().



--
-- http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
-- Mi sitio sobre programación web: http://bits.demogracia.com
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[C. (http://symcbean.blogspot.com/)]

Re: FP array checksum?

On Aug 7, 9:37 pm, "Álvaro G. Vicario"
<webmasterNOSPA MTHA...@demogra cia.comwrote:

*** la...@portcommo dore.com escribió/wrote (Thu, 7 Aug 2008 11:10:08 -0700
(PDT)):
>

I would like to generate a checksum for a small array of floating
point numbers (to see if there was a change in or not in the array,
without having to have all the original values in a form.) some sort
of CRC would be nice.

>

Any know of any sample code or suggestions?

>
You can use serialize() on the array to get a string and then apply a
hashing function like md5(), sha1() or crc32().
>
--
--http://alvaro.es- Álvaro G. Vicario - Burgos, Spain
-- Mi sitio sobre programación web:http://bits.demogracia.com
-- Mi web de humor en cubitos:http://www.demogracia.com
--

But floating point numbers change slightly when their representation
is altered; you can't assume that if x=1.00000000000 00/3.000000000000
then 3.0000000000000 *x = 3.0000000000000 000

So the solution needs to take into account what the meaning of
'change' is.

C.