What is your personal choice of method for calculating derivatives?
When estimating market movements in order to calculate derivatives, what is your personal choice of mathematical modeling, the Fourier series discrete or continuous model, discrete numerical methods, or basic calculus divergence and convergence ratios on Reimann sums and integrals, etc.? What formulation do you begin with to arrive at your error estimator, Maclaurin series, Taylor series with trailing errors, or Ostrowski's methods etc.?