From tomas.kalibera at gmail.com  Mon Feb 26 15:35:30 2018
From: tomas.kalibera at gmail.com (Tomas Kalibera)
Date: Mon, 26 Feb 2018 15:35:30 +0100
Subject: [Rd] Possible typo in the C source code of R
In-Reply-To: <7faca923-dfd9-19f6-7cff-3289bb4f715e@dim.uchile.cl>
References: <7faca923-dfd9-19f6-7cff-3289bb4f715e@dim.uchile.cl>
Message-ID: <2ce84680-f081-7d6f-efed-47829e69ace3@gmail.com>

Thank you, Martin, for spotting this, it is clearly a bug, originally a 
conformance check was intended here and time series were defined using 
integers, so exact comparison would have made sense. Now time series are 
defined using doubles and exact comparison could be too strict with 
rounding errors. Moreover, it is not clear whether a conformance check 
at this low-level is a good thing, so the check has been removed 
completely, keeping the current behavior of R (except NaNs in the 
definition).

Best
Tomas

On 02/07/2018 04:12 PM, Martin Bodin wrote:
> Good morning,
>
> I am Martin Bodin, a postdoc at the CMM in Santiago de Chile, and I am
> currently in the process of formalising (a part of) the R language into
> the Coq proof assistant. This work makes me look frequently at the
> source code of R.
>
> I have noticed a strange line in the file src/main/util.c of the trunk
> branch:
> https://github.com/wch/r-source/blob/e42531eff56ee6582d7dc6a46f242af5447c633e/src/main/util.c#L70
>
> The line 70 ?REAL(x)[0] == REAL(x)[0]? doesn?t make any sense for me:
> are we looking for NaN values here? I think that it should be
> ?REAL(x)[0] == REAL(y)[0]? instead (and the same applies for the next
> two lines).
>
> I didn?t searched for any R program that may be affected by this typo,
> but I have the feeling that it may lead to unexpected behaviours.
>
>  From what I understood, the bug reporting tool for R is closed for
> non-members, and I am thus sending this possible bug report in this
> list. Please redirect me if I am not reporting in the right place.
>
> Best regards,
> Martin Bodin.
>
>
>
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel



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[Rd] Possible typo in the C source code of R
Tomas Kalibera