Fields and Unit Conversion

Derived Fields

The following example creates a derived field for the square root of the cell volume.

No special unit logic needs to happen inside of the function - np.sqrt will convert the units of the density field appropriately:

That said, it is necessary to specify the units in the call to the add_field function. Not only does this ensure the returned units will be exactly what you expect, it also allows an in-place conversion of units, just in case the function returns a field with dimensionally equivalent units.

For example, let’s redo the above example but ask for units of Mpc**(3/2):