[klausb]

Why is this operation invalid and how can I fix it?

scalar rA_low = static_cast<float>(rA);

rA is a scalarField in PCG.C, and I need a float version of it which I call rA_low.

I get the following error message:

myMPPCG.C: In member function ‘virtual Foam::solverPerformance Foam::myMPPCG::solve(Foam::scalarField&, const scalarField&, Foam::direction) const’:

myMPPCG.C:115:42: error: invalid static_cast from type ‘Foam::scalarField {aka Foam::Field<double>}’ to type ‘float’
scalar rA_low = static_cast<float>(rA);

How can I create float versions of scalarFields which are of double type?

Klaus

[alexeym]

Hi,

scalarField is a field of scalars (or a list of scalars with certain additional operations defined). How you would like to convert a list into single value? If you know, that your field is uniform, then you can use just first element of the list. If your list is non-uniform, propose your way of converting arbitrary list of floats into single float.

[klausb]

Hello,

there's a misunderstanding. My question is about typecasting of the scalar field values.

I need another scalarField with typecast rA(double type values) to rA_low (float type values).

I tried the following to but that doesn't work either:

label rAsize = rA.size();
const scalarField rA_low(rAsize);
forAll(rA_low, i)
{
scalar s = static_cast<float>(rA[i]);
rA_low[i] = s;
}

Klaus

[alexeym]

I think it would be better to call it mis-explanation, cause this:

scalar rA_low = static_cast<float>(rA);

is an attempt to convert a field rA into a single float.

OK. It seems, your build is "DP", i.e. scalar is, let's call it alias of, double.

So

const scalarField rA_low(rAsize);

is a list of doubles. With

scalar s =  static_cast<float>(rA[i]);

you do static cast to float and then assign it to double.

Why no use Field<float> if you want field of floats? Or you can use floatScalar if you want to stay in OpenFOAM types.

Also it would be nice to decipher "that doesn't work either". Does not compile? Does not work as expected? Works from time to time?

[klausb]

Thank you for the hints.

Yes the build is DP.

And now I created an empty scalarField rA_low which can take values of type <float>:

label rAsize = rA.size();
floatScalar rA_low(rAsize);

The question is, how to typecast and load the data from rA into rA_low?

[alexeym]

It seems we are still do not understand each other.

What is wrong with, for example:

Field<float> rA_low(rA.size());
forAll(rA, i) { rA_low[i] = static_cast<float>(rA[i]); }

?

You are constantly trying to convert FIELD (i.e. list of numbers) into SCALAR (single number).

[klausb]

There's rA, a List which contains multiple entries in format <double>.

I need the same List with entries in format <float>, this one I call it rA_low.

The question is how to do such a "typecast conversion" with the List rA?

[alexeym]

So I repeat my question, what is wrong with type conversion in cycle?

[klausb]

An update, this seems to work:

List<float> rA_low(nCells);
for (int cell=0; cell<nCells; cell++)
{  
     rA_low[cell] = static_cast<float>(rA[cell]);
}