[R-pkg-devel] Fix JFM package problem

Hallo,

I wish to submit the following error rising running an example in a rcpp 
function *only *in Debian check:

### Name: least_square_plane_rcpp
### Title: returns the coefficients of the least square plane and the
###   relative medium square error
### Aliases: least_square_plane_rcpp

### ** Examples

list_xyz<-matrix(data = c(-10.0, -10.0, -15.0 ,10.0, -10.0,

+  -5.0, -10.0, 10.0, 5.0, 10.0, 10.0 ,15.0)
+ ,nrow = 4,ncol = 3, byrow = TRUE)

least_square_plane_rcpp(list_xyz)

warning: eig_sym(): given matrix is not symmetric
Error in least_square_plane_rcpp(list_xyz) :
   Mat::operator(): index out of bounds
Execution halted

This error raised also in window OS, but was fixed changing input 
variable in Rcpp::NumericMatrix.

Complete check is at:
https://win-builder.r-project.org/incoming_pretest/JFM_1.0_20220111_170553/Debian/00check.log

Every suggestion is welcome.

Thank you in advance

Best Regards

Riccardo