Proto for Boost mailing list page: Re: [proto] Manipulating an expression tree

Subject: Re: [proto] Manipulating an expression tree
From: Karsten Ahnert (karsten.ahnert_at_[hidden])
Date: 2011-04-08 08:11:01

Thank you for your example. I have one question: how do you use (or assign
something to) the intermediate values in StoredMatrixExpression?

> On Thu, Apr 7, 2011 at 12:45 AM, Karsten Ahnert
> <karsten.ahnert_at_[hidden]> wrote:
>> Another question is: can a node have a state. In my algorithm it would
>> be nice, if every proto::multiplies< > node stores some intermediate
>> values which are used during later evaluations of the tree.
>
> I did something similar to this to resolve the issue I had with the
> Eigen matrix library. I am replacing multiplies nodes with an
> expression that uses proto::extends to add extra state, in this case a
> correctly sized matrix to store the temporary matrix Eigen generates.
>
> I've attached the header that does the node replacement in all the
> cases that match the WrappableElementExpressions ("Wrap" in the header
> means replacing the node). Note that this header is ripped out of the
> context of a larger application (used for finite elements), so some
> stuff will not make sense, but the general idea might be helpful.
>
> I am using a primitive transform (WrapMatrixExpression) to do the
> actual node replacement here. An alternative would be to create a
> domain, and then use the make_... family of transforms to create nodes
> in that domain. I went for the primitive transform because it seemed
> to compile faster and with less memory.
>
> I intend to post a more detailed example on how I solved the problem
> with Eigen later on, with examples that are more stand-alone.
>
> Cheers,
>
> --
> Bart
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>

Karsten Ahnert
Ambrosys GmbH - Gesellschaft für Management komplexer Systeme
Geschwister-Scholl-Str. 63a
D-14471 Potsdam

Tel: [phone]
Fax: [phone]

Ambrosys GmbH - Gesellschaft für Management komplexer Systems
Gesellschaft mit beschränkter Haftung
Sitz der Gesellschaft: Geschwister-Scholl-Str. 63a, 14471 Potsdam
Registergericht: Amtsgericht Potsdam, HRB 21228 P
Geschäftsführer: Karsten Ahnert, Dr. Markus Abel

Karsten Ahnert
Ambrosys GmbH - Gesellschaft für Management komplexer Systeme
Geschwister-Scholl-Str. 63a
D-14471 Potsdam

Tel: [phone]
Fax: [phone]

Ambrosys GmbH - Gesellschaft für Management komplexer Systems
Gesellschaft mit beschränkter Haftung
Sitz der Gesellschaft: Geschwister-Scholl-Str. 63a, 14471 Potsdam
Registergericht: Amtsgericht Potsdam, HRB 21228 P
Geschäftsführer: Karsten Ahnert, Dr. Markus Abel