Direct differentiation method - negative gradient
 

Dear su2 people,

i'm doing verification analysis of AD discrete adjoint method on 3D two element wing model with FFD box. When i calculated objective function gradient by using forward direct differentiation method i found that it agrees with adjoint gradient (of Lift and Drag) only if i multiply it by -1 (see attachment).
Maybe it's relevant that in my model Y axis is aligned with Lift force direction, X - with drag and Z - with side force.
Is this just coincidence of wrong results or direct differentiation method calculates negative gradient?

Thanks,
Evgeniy