The Derivative Calculation method types for a Differential Corrector profile.

Member	Value	Description
eVADeriveCalcMethodForward	0	Forward Difference - (f(x + delta) - f(x - delta)) / 2delta
eVADeriveCalcMethodCentral	1	Central Difference - (f(x + delta) - f(x))/ delta
eVADeriveCalcMethodSigned	2	Signed Difference - if x is positive, use the forward difference; if x is negative, use the backward difference.