Hi all,

A while ago the Sage project reported a bug in basecase division in MPIR on
32 bit machines [1].

Since then we found a rare bug in basecase division on a 64 bit machine,
likely caused by the same issue.

Fortunately most modern x86_64 machines were tuned to not use the broken
implementation at all (k10 being an exception).

To fix this but I have simply removed the broken basecase division
implementation from MPIR altogether. It was rarely used and didn't provide
much of an improvement, so I decided it was best to just remove it.

The new divide-and-conquer routine remains in use of course, since that
gives a substantial improvement of around 20% over a significant range, and
no bugs are known in it.

As soon as we have checked if there are any other bits and pieces that need
to be put into the release, we will issue MPIR-2.7.1 to fix this issue.

In the mean time one can obtain a patched version of MPIR at my github [2].

I recommend all users upgrade as soon as we release MPIR-2.7.1.

Bill.

[1] http://trac.sagemath.org/ticket/19280
[2] https://github.com/wbhart/mpir

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