!DEC$ FREEFORM

SUBROUTINE eval(F1Old, F1, tempOld, temp, sysT, delta, S1, Jac, nPar, par, nStates1, states1, nStates2, states2) BIND(C,NAME="eval")
 
    use iso_c_binding
	
	IMPLICIT none
	
	!!! Declaration of COMSOL-parameters !!!
	INTEGER(kind=c_int), INTENT(in) :: nPar, nStates1, nStates2
	
	REAL(kind=c_double), DIMENSION(3,3), INTENT(in) :: F1Old, F1        ! Deformation gradient at current and previous step
	REAL(kind=c_double), DIMENSION(9), INTENT(in) :: sysT
	REAL(kind=c_double), INTENT(in) :: tempOld, temp, delta             ! Current temperature and reference temperature for strain
	
	REAL(kind=c_double), DIMENSION(nPar), INTENT(in) :: par
	REAL(kind=c_double), DIMENSION(nStates1), INTENT(inout) :: states1
	REAL(kind=c_double), DIMENSION(nStates2), INTENT(inout) :: states2
	
	REAL(kind=c_double), DIMENSION(6), INTENT(out) :: S1                ! Second Piola-Kirchhoff stress in local configuration
	REAL(kind=c_double), DIMENSION(6,9), INTENT(out) :: Jac             ! Jacobian
	
	
	S1 = 0._c_double 
	
	Jac = 0._c_double 
	Jac(1,1) = 1._c_double 
	Jac(2,2) = 1._c_double 
	Jac(3,3) = 1._c_double 
	Jac(4,4) = 1._c_double
	Jac(4,5) = 1._c_double
	Jac(5,6) = 1._c_double
	Jac(5,7) = 1._c_double
	Jac(6,8) = 1._c_double
	Jac(6,9) = 1._c_double    
	
	states1 = 0._c_double 
	states2 = 0._c_double 
	
END SUBROUTINE eval