It appears that in V2.00, log2(x) does not work in user defined functions. In fact, log(x) is actually ln(x). Is there any function for log10(x)?

For example, (f()*log2(x) + 4) does not work, but (f()*log(x)+4) works.

Also, when a perfect fitting function exits in the customized function, why R squared value becomes 0. In this case, R-squared value should be close to 1.0