Re: [Toon-members] TooN helpers.h

[E. Rosten]

On Thu, 16 Apr 2009, Gerhard Reitmayr wrote:

> be aware that this function won't work for slices etc. because they are 
> non-const temporaries. i.e.
>
> Vector<4> v;
> normalize(v.slice<0,3>()); // this will fail
>
> that's why we went with the unit function, for static vectors the compiler 
> generates the same code
> v.slice<0,3>() = unit(v.slice<0,3>());

The above code is efficient for static vectors (ie the compiler makes it 
work in-place), but not for dynamic ones.

If you compile the documentation and look at the section "Why don't 
functions work in place?", it goves a method for writing functions which 
work in-place.


> for Identity, the only working solution at the moment is:
>
> Matrix<10> m = Identity;
> m *= 22.0;
>
> We could do something like the following:
>
> Matrix<10> m = 22.0 * Identity;
>
> one alternative would be:
>
> Matrix<10> m = Identity(22.0);
>
> but this is already overloaded with identity for dynamic matrices where one 
> has to pass in the size at construction time:
>
> Matrix<> d = Identity(10);
>
> what do you guys think ?


How about a .diag() method which returns the leading diagonal as a slice?

-Ed

--
(You can't go wrong with psycho-rats.)(http://mi.eng.cam.ac.uk/~er258)

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