## Glas :## RE: [glas] Vector Spaces vs. "Objects called vectors" |

**From:** Edwards, Harold C (*hcedwar_at_[hidden]*)

**Date:** 2005-02-03 19:04:12

**Next message:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Previous message:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Maybe in reply to:**Edwards, Harold C: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Next in thread:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Reply:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Reply:**Toon Knapen: "Re: [glas] Vector Spaces vs. "Objects called vectors""

> Clearly, in a lot of cases it doesn't make sense to resize

> the vector.

> eg, "x += y", x and y should be the same size. The only case

> where it

> would be sensible to consider resizing is for ordinary

> assignment. Here,

> I don't think it is even sensible to fix a policy, if only for

> interoperability reasons (how would you prevent a resize for

> std::vector?

> How would you allow resize for a fixed-size array?).

Perhaps we can frame the "resize" concept in the

broader sense of "reassign vector space."

Some vector-implementations can be "morphed"

among a parameterized family of vector spaces while

other implementations are restricted to their initial

vector space.

Whether the vector-implementation is "morphable" should be

an observable characteristic of its implementation.

I don't believe it is a matter of whether or not to allow

"morphable" vector-implementations, but a matter of how best

to define and manage this characteristic.

> OTOH, partitioning and structure

> certainly are relevant and need to be included at some level in the

> concepts that the vector conform to.

These notions have been extremely useful in other efforts;

and are partially included in the Trilinos design.

http://software.sandia.gov/trilinos/.

--Carter

**Next message:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Previous message:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Maybe in reply to:**Edwards, Harold C: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Next in thread:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Reply:**Ian McCulloch: "RE: [glas] Vector Spaces vs. "Objects called vectors""**Reply:**Toon Knapen: "Re: [glas] Vector Spaces vs. "Objects called vectors""