Dear all,
I am trying to solve a compressible multi-species Navier-Stokes system with 9 unknowns, the system is in the form of (d: partial derivative )
(dU/dt)+(dFx/dx)+(dFy/dy)-(dGx/dx)-(dGy/dy)=S
where the conservation variables are presented in U, inviscid (Euler) fluxes in Fx, Fy, viscous fluxes are in Gx, Gy and the source terms in S.
I want to evaluate inviscid flux Jacobian (dFx/dU) where (dFx/dx)=(dFx/dU)(dU/dx)
I am wondering that whether it is as simple as just typing dFxdU = diff(Fx, U) or I am in trouble 
Thank you