Unexpected behaviour of eWiseApply([out] Matrix, [in] Matrix, [in] Matrix, ... ) variants

[byjtew]

An unexpected behaviour using the two variants of eWiseApply for matrices was noticed.

Documentation of the two variants

• eWiseApply([out] Matrix, [in] Matrix, [in] Matrix, [in] Monoid) is supposed to apply the given monoid's operator over all elements of the two matrices, including the {non_zero, zero} couples (UNION), using the provided monoid's identity as a replacement for the zero value.
• eWiseApply([out] Matrix, [in] Matrix, [in] Matrix, [in] Operator) is supposed to apply the given monoid's operator over all elements of the two matrices, except for the {non_zero, zero} couples (INTERSECTION).

The observed behaviour showed that only the INTERSECTION behaviour was implemented. A very user-friendly unit-test has been created for the occasion: eWiseApplyMatrix_variants.

Testing quickly:

make test_eWiseApplyMatrix_variants_debug_reference
./tests/unit/eWiseApplyMatrix_variants_debug_reference

Extra note: This unit-test should probably be re-evaluated.

[anyzelman]

A fix is in #204 , the unit test is also there