Stochastic differential equations (SDEs) have been applied by engineers and economists because it can express the behavior of stochastic processes in compact expressions. In this paper, by using Grunwald-Letnikov fractional derivative, the stochastic differential model is improved. Two numerical examples are presented to show efficiency of the proposed model. A numerical optimization approach based on least square approximation is applied to determine the order of the fractional derivative. Numerical examples show that the proposed model works better than the SDE to model stochastic processes with memory. Manuscript profile

The population growth, is increase in the number of individuals in population and it depends on some random environment effects. There are several different mathematical models for population growth. These models are suitable tool to predict future population growth. One of these models is logistic model. In this paper, by using Feynman-Kac formula, the Adomian decomposition method is applied to compute the moments for the solution of logistic stochastic differential equation. Manuscript profile

The forecast is very complex in financial markets. The reasons for this are the fluctuation of financial data, Such as Stock index data over time. The determining a model for forecasting fluctuations, can play a significant role in investors deci-sion making in financial markets. In the present paper, the Black Scholes model in the prediction of stock on year later value, on using data from mellat Bank and Ansar Bank shares in the year 2017-2018, in has been evaluated, and using a numerical method Euler Murayama and computer simulation with the Maple software, for simulated data, gained averages and Standard deviations, confidence interval and their normal histogram are plotted. Also, average of the answers obtained from computer simulations is compared with actual ones, and after ana-lyzing and reviewing the results, performance of the Black-Scholes model has been measured, in stock‌ value prediction. And in the end, this research is com-pared with internal article, and suggestions for future research are raised. Manuscript profile