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Fix BigInt to Float conversions #10139

Merged
merged 1 commit into from
Mar 18, 2015
Merged

Fix BigInt to Float conversions #10139

merged 1 commit into from
Mar 18, 2015

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simonbyrne
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Fixes #6365

StefanKarpinski
StefanKarpinski reviewed Feb 9, 2015
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base/float.jl

## checks if last bit is 0 or 1: used for IEEE rounding
is_ieee_even(x::Float64) = reinterpret(UInt64,x) & 1 == 0
is_ieee_even(x::Float32) = reinterpret(UInt32,x) & 1 == 0
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Maybe write these as is_ieee_even(x::Float64) = iseven(reinterpret(UInt64,x))?

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I have a slightly better solution.

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Yes, generic reinterpret is much better!

@simonbyrne
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I'm not sure what's causing the appveyor breakage.

@tkelman
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tkelman commented Mar 11, 2015

https://ci.appveyor.com/project/StefanKarpinski/julia/build/1.0.3095/job/8abr5wkvv2exgyla looks a little scarier than the usual case of #10045, but I just built this branch (only one time for now) locally on win32 without seeing it. I'll restart the appveyor build.

@simonbyrne
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Bump. Any thoughts?

cc: @StefanKarpinski

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Seems like a good thing to fix. Is there some potential downside? Otherwise just do it.

@simonbyrne
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It will require some intermediate allocation of BigInts, but only if the original argument is larger than 2^53. I can't really see any way around this.

simonbyrne added a commit that referenced this pull request Mar 18, 2015
@simonbyrne
Merge pull request #10139 from simonbyrne/bigint-float
288ea08 
Fix BigInt to Float conversions
@simonbyrne simonbyrne merged commit 288ea08 into JuliaLang:master Mar 18, 2015
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Successfully merging this pull request may close these issues.

convert(Float64, ::BigInt) – rounding and corner cases
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@simonbyrne @tkelman @StefanKarpinski