[ vDerivative ] = FiniteDifferenceFunctionDerivative( hFunction, fXAt, iDerivativeOrder, iOrderOfAccuracy, fStepSize)
    uses finite difference methods of different order to get a derivative
    at fXAt
    hFunction handler to function
    fXAt point at which derivativ will be calculated
    iDerivativeOrder 1-4 derivatives are possible
    iOrderOfAccuracy 2,4,6,8 for oreder 1-2, and 2, 4, 6 for 3-4 order -
    the accuracy is than fStepSize^iOrderOfAccuracy acurate
    fStepSize - h - distance between points of calculation.