[Proj] Proj 4.9.1RC4 Released

[Greg Troxel]

Howard Butler <howard at hobu.co> writes:

>> On Feb 24, 2015, at 9:00 PM, Greg Troxel <gdt at ir.bbn.com> wrote:
>> 
>> 
>> netbsd-6 i386:
>> 
>> diff tv_out with tv_out.dist
>> 313c313
>> < 13 -10        2073986.9490880956873   -1680858.2722242793534 0.0000000000000
>> ---
>>> 13 -10        2073986.9490880956873   -1680858.2722242795862 0.0000000000000
>> 
>> I am getting the same answer as the debian i386 boxes, I think.
>> 
>> This seems to be two parts in 10^16, and it seems unreasonable to expect
>> that from doubles after actual computation.
>
> I have updated the test precision, but I'm getting a weird either/or.
>
> x86_64 is returning 0.00000
> i386 is returning -0.00000
>
> accordingly, this makes it hard to set the test case.
>
> Any ideas?
>
> https://trac.osgeo.org/proj/ticket/255#comment:8

No good ideas, other than on amd64 with more registers more of the
computation is likely to be in 80-bit mode.   So +/- zero can end up
differently, and that's not necessarily wrong.

My current leaning is that for floating point tests, the only reasonable
thing to do is to have a range compare on the output.

It's not at all clear this should hold up a release, though.
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