dsetpk Subroutine

subroutine dsetpk(Neq, Y, Ysv, Ewt, Ftem, Savf, Jok, Wm, Iwm, f, jac)

DSETPK is called by DSTOKA to interface with the user-supplied routine JAC, to compute and process relevant parts of the matrix P = I - HEL(1)J, where J is the Jacobian df/dy, as need for preconditioning matrix operations later.

In addition to variables described previously, communication with DSETPK uses the following:

Y

array containing predicted values on entry.

YSV

array containing predicted y, to be saved (YH1 in DSTOKA).

FTEM

work array of length N (ACOR in DSTOKA).

SAVF

array containing f evaluated at predicted y.

JOK

input flag showing whether it was judged that Jacobian matrix data need not be recomputed (JOK = 1) or needs to be (JOK = -1).

WM

real work space for matrices. Space for preconditioning data starts at WM(LOCWP).

IWM

integer work space. Space for preconditioning data starts at IWM(LOCIWP).

IERPJ

output error flag, = 0 if no trouble, .gt. 0 if JAC returned an error flag.

JCUR

output flag to indicate whether the matrix data involved is now current (JCUR = 1) or not (JCUR = 0).

This routine also uses Common variables EL0, H, TN, IERPJ, JCUR, NJE.

Arguments

subroutine dsetpk(Neq,Y,Ysv,Ewt,Ftem,Savf,Jok,Wm,Iwm,f,jac)

integer       :: Neq(*)
real(kind=dp) :: Y(*)
real(kind=dp) :: Ysv(*)
real(kind=dp) :: Ewt(*)
real(kind=dp) :: Ftem(*)
real(kind=dp) :: Savf(*)
integer       :: Jok
real(kind=dp) :: Wm(*)
integer       :: Iwm(*)
external      :: f
external      :: jac

real(kind=dp) :: hl0
integer       :: ier

   dls1%ierpj = 0
   dls1%jcur = 0

   if ( Jok==-1 ) dls1%jcur = 1

   hl0 = dls1%el0*dls1%h
   call jac(f,Neq,dls1%tn,Y,Ysv,Ewt,Savf,Ftem,hl0,Jok,Wm(dlpk%locwp),Iwm(dlpk%lociwp),ier)
   dls1%nje = dls1%nje + 1

   if ( ier==0 ) return

   dls1%ierpj = 1

end subroutine dsetpk