[zhoubinwx]

Dear all,

We know that for log function:
dimentionedScalar log (const dimentionedScalar & ds)

I try to get the log value of (r/R), where r is the distance between the point and cylinder center, R is the cylinder radius.

When I take a look at "analyticalCylinder" in programmers' guide, we see that
r = volScalarField magCentres;
R = dimensionedScalar radius

However, magCentres/radius (or magCentres/radius.value()) is not dimentionedScalar, so my question is:
do we have log function for this case? Or how could I convert volScalarField into dimentionedScalar, which is required by log function?

Thank you for your attention.

Bin

[zhoubinwx]

This is solved.
Thank you for your attention.
Bin

[chiven]

Hi, dear Zhoubin, do you know how to convert dimentionedScalar into volScalarField? thanks. chiven

[l_r_mcglashan]

If you solve something, then state how you have solved it. There is NOTHING worse (in my opinion) on message boards than searching through threads such as this!

[isabel]

Hello friends,

I need to define the following variable; it is the natural logarithm of the time and a constant value:

volScalarField miso = ln(runTime+0.001);

But when I try to compile my solver I have the following error:

pdEqn.H:83: error: invalid initialization of reference of type ‘const Foam::fileName&’ from expression of type ‘Foam::dimensionedScalar’


Does anybody know what I have to do?

[l_r_mcglashan]

'ln' is not what you think it is. 'ln' is defined in openfoam as:

bool ln                      (           const fileName &             src,                              
          
          const fileName &             dst                              
          )

[isabel]

ln is the natural logarithm. I have successfully compiled my solver by introducing a surfaceScalarField unit variable:

miso = ln(unit*(runTime + 0.001*scalar(1))));

I am not sure if this is the best option.Does anyone have any better solution, or any comment?

[l_r_mcglashan]

I can't see how that works. Use 'Foam::log' which returns a dimensionedScalar and computes the natural logarithm.

[isabel]

Thank you very much. I prefer your suggestion.