Re: [eigen] maxCoeff taking reference?

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

We must make sure that this does not introduce overhead if the index(es) 
is not used. Perhaps with some template magic it is possible to 
distinguish calling

   auto [value, row,col] = A.maxCoeff();
vs
   auto value = A.maxCoeff();

This would actually be very close to how Matlab "overloads" many 
functions. If that is not possible, we could of course just give one 
method a different name.

Btw: I agree on not overloading for references, as it should be obvious 
that these are out-parameters. O.t.o.h., with pointers there is always 
the ambiguity if null-pointers are allowed or not.

Christoph

On 22/03/2019 09.45, Gael Guennebaud wrote:
> We chose pointers to emphasise they are out parameters. I would not add
> overloads taking references but maybe a version returning everything within
> a struct to be used with C++17 structure bindings?
>
> On Thu, Mar 21, 2019 at 3:27 AM Meng Zhu <meng@xxxxxxxxxxxxx> wrote:
>
> > hi, I noticed eigen maxCoeff function (
> > https://eigen.tuxfamily.org/dox/classEigen_1_1DenseBase.html#a784e23ccbb39e7c57b70af386f94f8b5)
> > takes pointers to return the max entry coord, and there is no overload to
> > take reference type. is there a reason to not provide reference access?
> > thanks.
> >
> > Meng

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