Fix eigen copying of non-standard stride values
Some Eigen objects, such as those returned by matrix.diagonal() and
matrix.block() have non-standard stride values because they are
basically just maps onto the underlying matrix without copying it (for
example, the primary diagonal of a 3x3 matrix is a vector-like object
with .src equal to the full matrix data, but with stride 4). Returning
such an object from a pybind11 method breaks, however, because pybind11
assumes vectors have stride 1, and that matrices have strides equal to
the number of rows/columns or 1 (depending on whether the matrix is
stored column-major or row-major).
This commit fixes the issue by making pybind11 use Eigen's stride
methods when copying the data.
diff --git a/example/eigen.ref b/example/eigen.ref
index 93e88ad..8ccd1f4 100644
--- a/example/eigen.ref
+++ b/example/eigen.ref
@@ -33,3 +33,20 @@
cholesky4 OK
cholesky5 OK
cholesky6 OK
+diagonal() OK
+diagonal_1() OK
+diagonal_n(-5) OK
+diagonal_n(-4) OK
+diagonal_n(-3) OK
+diagonal_n(-2) OK
+diagonal_n(-1) OK
+diagonal_n(0) OK
+diagonal_n(1) OK
+diagonal_n(2) OK
+diagonal_n(3) OK
+diagonal_n(4) OK
+diagonal_n(5) OK
+diagonal_n(6) OK
+block(2,1,3,3) OK
+block(1,4,4,2) OK
+block(1,4,3,2) OK