How accurate must a returned result be to be accepted?

Please do not laugh, I am serious.

From posts in the programmer's threads, I know that each client produces slightly different results depending on which processor does the processing. MMX-SSE stuff, Linux - Windows - Mac You know.

To check things out, I am right now trying to make 2 of my machines crunch the same WU. One Athlon XP and an Intel PII MMX, just to see if they return exactly the same figures, or they differ in the 7th or 8th digit.

However, if the 'Coding people' reads this, they might save me the hazzle by telling me right away. :)

ChrisD

> How accurate must a returned result be to be accepted?
>
> Please do not laugh, I am serious.
>
> From posts in the programmer's threads, I know that each client produces
> slightly different results depending on which processor does the processing.
> MMX-SSE stuff, Linux - Windows - Mac You know.
>
> To check things out, I am right now trying to make 2 of my machines crunch the
> same WU. One Athlon XP and an Intel PII MMX, just to see if they return
> exactly the same figures, or they differ in the 7th or 8th digit.

For SETI@Home, you will get minor fluctuations because of the FPUs not delivering the precicely identical values. What the validator is going to do is check to see if you found the same spikes, Gaussians, etc. in the work unit that the other participants did when they processed that same WU.

If you find the same number of spikes but yours is less than, or greater than, theirs by some %, depending on how large that error is will either say it was valid, or reject it.

Like wise with spike and Gaussian detection if you "find" some they don't it is more than likely more than a rounding problem.

The vaildation is project dependent and can be very strict (LHC@Home has this problem).
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> The vaildation is project dependent and can be very strict (LHC@Home has this
> problem).

I think that with the new release of the LHC client, this issue has been fixed.

> I think that with the new release of the LHC client, this issue has been
> fixed.

They opened the limits by some amount. But it is such a problem that they told me that would be no Macintosh application because of the differrences in the values returned.
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