[ vDerivative ] = FiniteDifferenceFunctionDerivative( hFunction, fXAt, iDerivativeOrder, iOrderOfAccuracy, fStepSize)
uses finite difference methods of different order to get a derivative
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.