Linear algebra support in stdlib

[Beliavsky]

@hkvzjal

@FedericoPerini

I like optional keywords but I think someone pointed out that they may be slow, because they’re evaluated at runtime? So I’m thinking whether generic interfaces, or a settings structure, may work better?

I also like optionals, it is true that they have a small overhead to verify the presence of the optional argument, but is it that slow? not sure, I guess the answer is “it depends” (on the ratio of processed data vs number of calls).

This question was discussed in the thread Testing whether an argument is PRESENT is very fast .