if x=t why are you using both in the same function? If you don't simplify your energy function alot of people will be turned off by the apparent complexity. It should read P(t)dt and V(t)dt. Also since your function describes the distribution of energy in the stock market, wouldn't it be logical to calculate the entropy also? high entropy would means alot of inefficiency is present in the market, thus alot more money to gain from it