Logarithm in dolfinx

Hello everyone, could anyone please inform about how to calculate the logarithm of variable and not the ufl.ln. My desired equation with logarithm is ,
image
Unfortunately I am not finding any in the ufl. So if anyone has an idea over this, do please tell me. Thanks in advance.

The question is unclear. My understanding of it is that you are not interested in the natural logarithm, but a log in another base. If that is the case, just use the change of base formula.

As Francesco is saying, you can convert to any logarithm, for instance the base 10 logarithm with:

def log(x):
    return 1/ ufl.ln(10) * ufl.ln(x)