Additional chol() method for compatibility

[jdlangs]

#10862 changed the interface of chol to use a Val argument for dispatching. However, the documentation still specifies using a Symbol argument. This just adds an indirection method that converts the symbol to a Val, thereby keeping the old user interface and documentation intact.

[jiahao]

Why not just update the documentation?

[jdlangs]

I thought it was better to keep backwards compatibility available. Is there value in requiring people to switch their code to use Val?

[jiahao]

Fair enough.

I think this is good to merge unless @andreasnoack has any objections.

[andreasnoack]

Yes, there is a value in requiring Val here, but the documentation should, of course, have been updated. The reason for requiring Val is that the return type of chol depends on the uplo argument (UpperTriangular or LowerTriangular). I'm not a super fan of Val{true}/Val{false}, but there is not an obviously better option. We could use chol(A, LowerTriangular), but that is a bit long.

[jdlangs]

That makes sense. I had thought it was just for dispatching but the type stability is definitely worth having.

I can perform my penance by turning this PR into a docs update.

[andreasnoack]

That would be great.

[jdlangs]

Branch has been updated.

[andreasnoack]

Great. Thanks.