math.log takes two arguments. The first argument is a value you want to create the log value for and the second argument represents the base to which the logarithm will be computed.
You have tried to call a function named math.log2 but that does not exist. Also, if you want to use the functions contained in the math module, you will need to import it first.
cos is part of the math module, so you will need to prefix it with math.
Lastly, the float function expects a string as its argument, and what you supplied is not a string. By the way, math.e is not a function. It is a constant, so you can not call it as a function with an argument.