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author | Gael Guennebaud <g.gael@free.fr> | 2015-09-02 11:23:55 +0200 |
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committer | Gael Guennebaud <g.gael@free.fr> | 2015-09-02 11:23:55 +0200 |
commit | aba8c9ee176de6821ab483a0f284f725e0e5d603 (patch) | |
tree | 94bf466853f3f8abdaca54c06451abfa629fff3a /doc/Pitfalls.dox | |
parent | a75616887ecce116639e332d476deafc7d833d67 (diff) |
Add a documentation page for common pitfalls
Diffstat (limited to 'doc/Pitfalls.dox')
-rw-r--r-- | doc/Pitfalls.dox | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/doc/Pitfalls.dox b/doc/Pitfalls.dox new file mode 100644 index 000000000..203843ca7 --- /dev/null +++ b/doc/Pitfalls.dox @@ -0,0 +1,22 @@ +namespace Eigen { + +/** \page TopicPitfalls Common pitfalls + +\section TopicPitfalls_template_keyword Compilation error with template methods + +See this \link TopicTemplateKeyword page \endlink. + +\section TopicPitfalls_auto_keyword C++11 and the auto keyword + +In short: do not use the auto keywords with Eigen's expressions, unless you are 100% sure about what you are doing. In particular, do not use the auto keyword as a replacement for a Matrix<> type. Here is an example: + +\code +MatrixXd A, B; +auto C = A*B; +for(...) { ... w = C * v; ...} +\endcode + +In this example, the type of C is not a MatrixXd but an abstract expression representing a matrix product and storing references to A and B. Therefore, the product of A*B will be carried out multiple times, once per iteration of the for loop. Moreover, if the coefficients of A or B change during the iteration, then C will evaluate to different values. + +*/ +} |