Difference between revisions of "Pit Falls"

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= Pit Falls =
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Moved there: http://eigen.tuxfamily.org/dox-devel/TopicPitfalls.html
 
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== Alignment Issues (runtime assertion) ==
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Eigen does explicit vectorization, and while that is appreciated by many users, that also leads to some issues in special situations where data alignment is compromised. Indeed, C++98 doesn't have quite good enough support for explicit data alignment (that's coming in C++1x). In that case your program hits an assertion failure (that is, a "controlled crash") with a message that tells you to consult this page:
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  [http://eigen.tuxfamily.org/dox/UnalignedArrayAssert.html http://eigen.tuxfamily.org/dox/UnalignedArrayAssert.html]
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Have a look at it and see for yourself if that's something that can cope with. It contains detailed information about how to deal with each known cause for that issue.
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Now what if you don't care about vectorization and so don't want to be annoyed with these alignment issues? Then you can easily [[FAQ#I_disabled_vectorization.2C_but_I.27m_still_getting_annoyed_about_alignment_issues.21|get rid of them]].
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== Header Issues (failure to compile) ==
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With all libraries, one must check the documentation for which header to include. The same is true with Eigen, but a little worse: with Eigen, a '''methods''' in a class may require an additional #include over what the class itself requires! For example, if you want to use the [http://eigen.tuxfamily.org/dox/classEigen_1_1MatrixBase.html#e09fde9d844e0eb8248955b3a2754272 cross]() method on a vector (it computes a cross-product) then you need to
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  #include<Eigen/Geometry>
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We try to always document this, but do tell us if we forgot an occurence.
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Latest revision as of 12:26, 30 January 2019

Moved there: http://eigen.tuxfamily.org/dox-devel/TopicPitfalls.html