Re: [Psidev-ms-dev] PSI-MSS WG Tuesday call reminder

[Brian P. <bri...@in...>]

The goal of "round trip" is best served by the binary representation.  Keep
in mind that these values come off the machine as IEEE floats, not tidy
human readable representations.  The value you think of as "1.5" is actually
a bit pattern that may well have the value 1.5000001, but (assuming a chain
of conversion that never attempts a human readable representation) it's the
same bit pattern that came off the mass spec, so it's the "right" one.  

- Brian

-----Original Message-----
From: Mike Coleman [mailto:tu...@gm...] 
Sent: Thursday, June 11, 2009 1:41 PM
To: Mass spectrometry standard development
Subject: Re: [Psidev-ms-dev] PSI-MSS WG Tuesday call reminder

I took it to mean that with "1", "1.5", "1.50", one gets an implied
level of precision.  That is, "1.5" is generally understood to mean
1.5 +/- 0.05.  If I give you the IEEE float 1.5, much less is implied
about the precision of this value, unless it's explicitly stated
elsewhere.  (If you have a whole set of these, then you probably can
work out the equivalent precision, but this is a bit of a stretch.)

Mike


On Thu, Jun 11, 2009 at 3:23 PM, Angel Pizarro<an...@ma...>
wrote:
> Is your question whether we can successfully round-trip the numbers? Eg.
go
> from an ascii format to mzML back to originating ascii format and get the
> same exact numbers? I believe that when we pack the numbers and unpack
them
> (at least in my non-validating ruby implementations) the numbers and
> significance are completely the same. E.g. 1.005 === 1.005 and not
> 1.005000000000001
> -angel

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