new matrix classes for R 4.0.0

[topepo]

Dear maintainer,

Please see the problems shown on
https://cran.r-project.org/web/checks/check_results_recipes.html.

Specifically, see the problems shown for the r-devel Debian checks.

These can be reproduced by checking with --as-cran using current
r-devel, which for now sets

_R_CLASS_MATRIX_ARRAY_=true 

in the check environment, to the effect that

R> class(matrix(1 : 4, 2, 2)) 
[1] "matrix" "array" 

(and no longer just "matrix" as before).

According to the R NEWS file,

For now only active when environment variable R_CLASS_MATRIX_ARRAY
is set to non-empty, but planned to be the new unconditional behavior
when R 4.0.0 is released:

matrix objects now also inherit from class "array", namely, e.g.,
class(diag(1)) is c("matrix", "array") which invalidates code
assuming that length(class(obj)) == 1, an incorrect assumption that
is less frequently fulfilled now.

S3 methods for "array", i.e., <someFun>.array(), are now also
dispatched for matrix objects.

Apparently your package no longer works correctly when
class(matrix(...)) gives a vector of length two: please fix as
necessary.

See
https://developer.r-project.org/Blog/public/2019/11/09/when-you-think-class.-think-again/index.html
for more information about correctly using class() in package code.

Please correct before 2019-12-18 to safely retain your package on CRAN.

[topepo]

Closed by 830b55d

[github-actions]

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