### COMSOL Multiphysics 3.3

I was a little slow to notice the release of a new version of COMSOL Multiphysics. The simulation software, which was until last year sold under the name of FEMLAB, was updated over a month ago.

The new features are quite numerous and you can read them here.

Broadly speaking, they mostly involve trying to widen the space of applications further away from the original finite element modelling background of the company, eg with optimization and signal processing.

There is also some work on improving core functionality with work on adaptive meshes.

All very sensible.

## 2 comments:

Hi! Please, can you help me with a little issue. I am working with the multiphysics modelling of femlab: Stokes problem, and I need the matrices of the bilinear form, gradient and divergence to create a matlab program. Could you tell me how can I have this information in the workspace of matlab and how can I use this information to set up a program?

Hi!

I am a beginner in working with COMSOL.

I want to ask how can I use a function in defining a global expression.

For example I have several functions, depending on the space: fHx, fBx, fQx =f(x), which I take it from a .txt file.

1. first question

I use them to define some other parameters. I write in global expressions like this:

fvx = fQx(x)/(fHx(x)*fBx(x))

fDx = fBx(x)/(fvx*constant)

COMSOL is computing, but I am not sure is k, because in the end when I want to plot fvx and fDx, form Global variables plot it gives an error: 8032 fvx is not a valid globla expression.

This means that there is the possibility also to compute it wrong along x axis.

2.

I want to calculate a parameter in one point (x=103), depending on the functions I implemented. In global expression I write

c_103 = (fQx(103)*c+constant)/(fQx(103)+constant)

c is the dependent variable of the model.

The expression is computed, but I don't trust is k. The same warning when I try to plot it.

Any suggestions would be of great help!

Regards

Cristina

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