Re: [sage-devel] Re: sage built with icc/icpc/gfortran

2017-06-28 Thread kcrisman
This is all good news, even if nobody will actually use icc.  Nice work!

Definitely numerical noise. 
> sage: q = RDF.pi()/3 
> sage: i = q.cos() 
> sage: q - i.arccos() 
> -2.220446049250313e-16 
>
> Is this supposed to be exact? 
>

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[sage-devel] Re: Jupyter notebook: typeset formulas in pdf-export

2017-06-28 Thread kcrisman


>
> As Jupyter is becoming the default notebook in Sage 8.0, 
>

Though as Jeroen points out, technically the default is the export 
functionality from sagenb to Jupyter ...
 

> I guess it would be nice to fix this, otherwise many users could be quite 
> disappointed when getting such a bad pdf export of their notebooks.
> I've opened the ticket
> https://trac.sagemath.org/ticket/23330
> although I've no clue how to proceed. According to Nils' explanation, this 
> could be on the Jupyter side...
>

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Re: [sage-devel] Re: sage built with icc/icpc/gfortran

2017-06-28 Thread Thierry Dumont

Be careful with icc compiler family.

It is relatively frequent to get small differences between gcc and icc
floating (double/float) computations.A specialist of floating point said
that icc build faster programs fro two reasons:
1) Intel knows his processors,
2) they make excessive assumptions on floating point expression (more or
less that addition is associative, something like fast-math option in gcc).
t.

Le 28/06/2017 à 04:42, François Bissey a écrit :
> 
> 
> On 28/06/17 10:51, François Bissey wrote:
>> with the peculiar being:
>> **
>> File "src/sage/rings/real_double.pyx", line 2296, in
>> sage.rings.real_double.RealDoubleElement.arccos
>> Failed example:
>> i.arccos() == q
>> Expected:
>> True
>> Got:
>> False
>> **
>> If anyone has an idea.
> 
> Definitely numerical noise.
> sage: q = RDF.pi()/3
> sage: i = q.cos()
> sage: q - i.arccos()
> -2.220446049250313e-16
> 
> Is this supposed to be exact?
> 

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