# Setting cell membrane fluctuation ona cell-by-cell basis¶

As you probably know the (in)famous Temperature parameter used in CPM modeling represents cell membrane fluctuation amplitude. When you increase temperature cell boundary gets jagged and if you decrease it cells may freeze. One problem with global parameter describing membrane fluctuation is that it applies to all cells. Fortunately in CC3D you may set membrane fluctuation amplitude on per-cell-type basis or individually for each cell. The code that does it is very simple:

cell.fluctAmpl = 50


From now on all calculations involving the cell for which we set membrane fluctuation amplitude will use this new value. If you want to undo the change and have global temperature parameter describe membrane fluctuation amplitude you use the following code:

cell.fluctAmpl = -1


In fact, this is how CC3D figures out whether to use local or global membrane fluctuation amplitude. If fluctAmpl is a negative number CC3D uses global parameter. If it is greater than or equal to zero local value takes precedence.

In Twedit++ go to CC3D Python->Cell Attributes-> Fluctuation Amplitude in case you forget the syntax.