EIGEN_DEFAULT_TO_ROW_MAJOR and other flags

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp, r
Domain
data

Research direction

Start with the EIGEN_DEFAULT_TO_ROW_MAJOR definition and the RcppEigen.h include in the reported Rcpp example, checking how macro placement affects the generated matrix layout. Compare the result with R's column-major behavior; done means the supported configuration or limitation is established and documented or tested.

Written by the indexing model from the issue text.

Description

I'm interfacing with a legacy C++ code which sets EIGEN_DEFAULT_TO_ROW_MAJOR (well known to break compatibility) but, basic searching and playing with defining the macro doesn't seem to help at all in R, matrices are still in column order and have to be manually reshaped (say matrix(byrow=T, ncol=3)).

I could wrap this thing in an R class and deal with this there every-time but was hoping I might have missed a way of setting the flag.

Things I tried:

#define EIGEN_DEFAULT_TO_ROW_MAJOR
#include <RcppEigen.h>
// [[Rcpp::depends(RcppEigen)]]

And moving it after the #include or the comment also does not help.

Dominant language
C++
Stars
118
Forks
43
No merged PRs in 30d

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