Operator == does not check for size and incorrectly returns true for comparison of (partically) dynamic matrix with random matrix. TEST(A, B) { typedef Eigen::Matrix<double, 10, Eigen::Dynamic> Type; Type a; a.setRandom(10, 5); Type b; EXPECT_FALSE(a == b); // Fails. Type c; c.setRandom(10, 5); EXPECT_FALSE(a == c); // Passes. } TEST(A, C) { typedef Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic> Type; Type a; a.setRandom(10, 5); Type b; EXPECT_FALSE(a == b); // Fails. Type c; c.setRandom(10, 5); EXPECT_FALSE(a == c); // Passes. }
So far, we had a==b be equivalent to a.cwiseEqual(b).all(), which means we assume (and assert) that the sizes match. But checking for matching sizes before that actually makes sense (and I doubt it would break anything). Should we want to keep the current behavior, we must at least document it. If we change it, we should suggest the alternative .cwiseEqual().all(), in case someone really wishes to avoid the minor overhead of checking the dimension first.
Such a change would make operator== equivalent to Matlab's isequal behavior, so why not. Another solution would be to add a isEqual() member (and maybe even a isEqualN() to deal with NaN) mimicking Matlab's isequal*, but if we do so, then for consistency we should probably also update isApprox to check for the size first.
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