[anton_lias]

Hello everybody,
I want to create a volTensorField out of a couple of volScalarFields. The tensor should look (for example) like this JacobiMatrix=(m1, m2+m1, 0, m5*m3, m4, 0, m0, m2/m1, m2).

The Moments m0-m5 are defined like this

	Info<< "Reading field m0" << endl;
	volScalarField m0
	(
		IOobject
		(
			"m0",
			runTime.timeName(),
			mesh,
			IOobject::MUST_READ,
			IOobject::AUTO_WRITE
		),
		mesh
	);

I have tried a lot of things, but I do not manage to create the Tensor.
For example:

	Info<< "Define tensorfield jacobiMatrix" << endl;
	volTensorField jacobiMatrix
	(
		IOobject
		(
			"jacobiMatrix",
			runTime.timeName(),
			mesh,
			IOobject::NO_READ,
			IOobject::NO_WRITE
		),
		mesh,
		dimensionedTensor
		(
			"zero",
			dimensionSet(0, 0, 0, 0, 0, 0, 0),
			tensor::zero
		)
	);

and

jacobiMatrix.component(0) = m1;
jacobiMatrix.component(1) = m2+m1;
…

The Solver is compiling, but when I use it, an error message appears.

--> FOAM FATAL ERROR:
attempted to assign to a const reference to constant object

Does anyone know, how I could create a volTensorField out of the volScalarFields?

[JimKnopf]

You could do a loop over all cells and then compute your components like:

// const Foam::cellList cells = mesh.cells()
forAll(cells,cellI)
{
JacobiMatrix[cellI].component(0) = m1[cellI]+m2[cellI];
// same for all the others
}

This probably no good style but it should work.

Best Regards
Jim

[anton_lias]

Thanks a lot, it is working.
But I have to write
forAll(mesh.cells(),cellI)
{...

I already read that it's not a good style. But I did not find an answer on the question, how a good style would look like.

[JackW]

I know this is an old post, but did you (or anyone else) find a more compact solution to this problem? Would be much appreciated!

[deepsterblue]

What you're looking for here is the replace() member function:

jacobiMatrix.replace(0, m0);
jacobiMatrix.replace(1, m1);
jacobiMatrix.replace(2, m2);
...
...
jacobiMatrix.replace(8, m8);

No need to loop over all cells.

[JackW]

Brilliant, thanks!