Re: reduction funs optimizations + min/max question

[Søren Hauberg]

tir, 17 02 2009 kl. 08:56 +0100, skrev Jaroslav Hajek:
> Well, it would take some work, but seems relatively straightforward.

I would consider this a very low-priority task. I was mainly asking
because if it was nothing more than a few lines of code, then these
functions would be nice to have. But I'm guessing that these functions
would only be used rarely.

> We'd need to settle on a specification, though.
> So, my idea:
> y = cummax (x, dim);
> returns cumulative maximum along dimension dim. If dim is omitted,
> operates along the first non-singleton dimension.
> [y, i] = cummax (x);
> returns also cumulative maximum indices.
> cummin is analogical.

This seems like the obvious choice.

> So, the question is: Is it worth doing this for 3.2?

I'd consider this low priority.

> It seems to me that this function cannot be reasonably simulated in
> m-code without using a loop or sacrificing the O(N) complexity. Can
> anyone elaborate on expected usage?

I cannot remember the expected usage. I could probably see some uses of
such functions in image analysis, where you easily work with large
matrices, in which a loop implementation would be too slow to be of any
use.

Soren