A variable is a physical quantity that can be computed by
*CrysMAS* , like
**Temperature** or
**vonMisesStress**. Some of this variables are closely related to each other
while others are practically independent from each other.

For instance, the two components of displacements are coupled very tight together
because they are influencing each other and can be solved only together. They are also
both coupled to the
**Temperature** but the temperature is independent of them, so the
relationship between the displacements and the
**Temperature** is not very tight because the only condition that
must be fulfilled is that first the temperature must be computed and afterwards
the displacements.

The
**vonMisesStress** can again be computed from the displacements.
There are cases when the user must decide how strong the variables are coupled together.
For instance, the user might need to compute the temperature and the magnetic field
at the same time if the magnetic properties are depending on the temperature.
Else, the user can choose to compute first the magnetic field and then the temperature.

This is the reason that some variables are coupled together in groups of variables.

A group of variables contains all variables which are calculated simultaneously.
For instance, the variable group
**Temperature** contains radial gradient, axial gradient, radial heat flux,
axial heat flux, conductivity r and conductivity z.

After selecting the desired variable group, you must specify the region(s) where
the program should calculate them. On the one hand, not every variable is of interest
for all regions. On the other hand, it is not possible to calculate every variable for
every region respectively material. You determine which groups of variables are
of interest in a region by using the
**Physical Phenomena** dialog invoked via
**Settings** menu.