# How to use natural logarithm inside Expression on FENICS

I'm trying to evaluate the exact solution of heat diffusion in circular plate.

I'm not able to use the natural logarithm inside expression.

from math import log as ln

u_e = Expression("ln(5)")


The above line doesn't work. Could anyone help me with the correct syntax?

Double quotes(" ") represent strings in python, and hence the argument of the function Expression() is a string literal rather than a floating-point number, i.e., ln(5). To correctly specify ln(5) as an argument, remove the double-quotes.
import math