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Document EIGEN_NO_DEBUG macro.

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I needed some doxygen tricks to get this to work, so it may not be worth it.
This commit is contained in:
Jitse Niesen
2010-08-10 11:37:23 +01:00
parent 530b328769
commit 76fbe94279
5 changed files with 26 additions and 7 deletions
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8
doc/I11_Aliasing.dox
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@@ -46,7 +46,7 @@ the blocks <tt>mat.bottomRightCorner(2,2)</tt> and <tt>mat.topLeftCorner(2,2)</t
contain the coefficient <tt>mat(1,1)</tt> at the centre of the 3-by-3 matrix \c mat . The next section
explains how to solve this problem by calling \link DenseBase::eval() eval()\endlink.
Note that if \c mat were a bigger, then the blocks would not overlop, and there would be no aliasing
Note that if \c mat were a bigger, then the blocks would not overlap, and there would be no aliasing
problem. This means that in general aliasing cannot be detected at compile time. However, Eigen does detect
some instances of aliasing, albeit at run time. The following example exhibiting aliasing was mentioned in
\ref TutorialMatrixArithmetic :
@@ -61,15 +61,15 @@ Output: \verbinclude tut_arithmetic_transpose_aliasing.out
Again, the output shows the aliasing issue. However, by default Eigen uses a run-time assertion to detect this
and exits with a message like
\code
\verbatim
void Eigen::DenseBase<Derived>::checkTransposeAliasing(const OtherDerived&) const
[with OtherDerived = Eigen::Transpose<Eigen::Matrix<int, 2, 2, 0, 2, 2> >, Derived = Eigen::Matrix<int, 2, 2, 0, 2, 2>]:
Assertion `(!ei_check_transpose_aliasing_selector<Scalar,ei_blas_traits<Derived>::IsTransposed,OtherDerived>::run(ei_extract_data(derived()), other))
&& "aliasing detected during tranposition, use transposeInPlace() or evaluate the rhs into a temporary using .eval()"' failed.
\endcode
\endverbatim
The user can turn Eigen's run-time assertions like the one to detect this aliasing problem off by defining the
EIGEN_NO_DEBUG macro, and the above program was compiled with this macro turned off in order to illustrate the
#EIGEN_NO_DEBUG macro, and the above program was compiled with this macro turned off in order to illustrate the
aliasing problem. See \ref TopicAssertions for more information about Eigen's run-time assertions.