dvode_data_t Derived Type

   type,public :: dvode_data_t

      !! Internal variables for DVODE.
      !! variables which are communicated between subroutines in the
      !! dvode package, or which are to be saved between calls to dvode.

      private

      ! type declarations formerly in common block dvod01
      real(wp) :: acnrm   = zero !! weighted r.m.s. norm of accumulated correction vectors.
      real(wp) :: ccmxj   = zero !! threshhold on drc for updating the jacobian. (see drc.)
      real(wp) :: conp    = zero !! the saved value of tq(5).
      real(wp) :: crate   = zero !! estimated corrector convergence rate constant.
      real(wp) :: drc     = zero !! relative change in h*rl1 since last dvjac call.
      real(wp) :: el(13)  = zero !! real array of integration coefficients.  see dvset.
      real(wp) :: eta     = zero !! saved tentative ratio of new to old h.
      real(wp) :: etamax  = zero !! saved maximum value of eta to be allowed.
      real(wp) :: h       = zero !! the step size.
      real(wp) :: hmin    = zero !! the minimum absolute value of the step size h to be used.
      real(wp) :: hmxi    = zero !! inverse of the maximum absolute value of h to be used.
                                 !! hmxi = 0.0 is allowed and corresponds to an infinite hmax.
      real(wp) :: hnew    = zero !! the step size to be attempted on the next step.
      real(wp) :: hscal   = zero !! step size `h` used in scaling of nordsieck array `yh` in [[dvjust]].
                                 !! (if `iord = +1`, [[dvjust]] assumes that `hscal = tau(1)`.)
                                 !! see references 1 and 2 for details.
      real(wp) :: prl1    = zero !! the saved value of rl1.
      real(wp) :: rc      = zero !! ratio of current h*rl1 to value on last dvjac call.
      real(wp) :: rl1     = zero !! the reciprocal of the coefficient el(1).
      real(wp) :: tau(13) = zero !! real vector of past nq step sizes, length 13.
      real(wp) :: tq(5)   = zero !! a real vector of length 5 in which dvset stores constants
                                 !! used for the convergence test, the error test, and the
                                 !! selection of h at a new order.
      real(wp) :: tn      = zero !! the independent variable, updated on each step taken.
      real(wp) :: uround  = zero !! the machine unit roundoff.  the smallest positive real number
                                 !! such that  1.0 + uround /= 1.0
      integer :: icf      = 0 !! integer flag for convergence failure in dvnlsd:
                              !!
                              !!  * 0 means no failures.
                              !!  * 1 means convergence failure with out of date jacobian
                              !!    (recoverable error).
                              !!  * 2 means convergence failure with current jacobian or
                              !!    singular matrix (unrecoverable error).
      integer :: init     = 0 !! saved integer flag indicating whether initialization of the
                              !! problem has been done (init = 1) or not.
      integer :: ipup     = 0 !! saved flag to signal updating of newton matrix.
                              !!
                              !! In [[dvnlsd]]: own variable flag with values and meanings as follows:
                              !!
                              !!  * 0, do not update the newton matrix.
                              !!  * `miter /= 0`, update newton matrix, because it is the
                              !!    initial step, order was changed, the error
                              !!    test failed, or an update is indicated by
                              !!    the scalar `rc` or step counter `nst`.
      integer :: jcur     = 0 !! output flag from [[dvjac]] showing jacobian status:
                              !!
                              !!  * jcur = 0 means j is not current.
                              !!  * jcur = 1 means j is current.
      integer :: jstart   = 0 !! integer flag used as input to dvstep:
                              !!
                              !!  * 0  means perform the first step.
                              !!  * 1  means take a new step continuing from the last.
                              !!  * -1 means take the next step with a new value of maxord,
                              !!    hmin, hmxi, n, meth, miter, and/or matrix parameters.
                              !!
                              !! on return, dvstep sets jstart = 1.
      integer :: jsv      = 0 !! integer flag for jacobian saving, = sign(mf).
      integer :: kflag    = 0 !! a completion code from dvstep with the following meanings:
                              !!
                              !!  *  0      the step was succesful.
                              !!  * -1      the requested error could not be achieved.
                              !!  * -2      corrector convergence could not be achieved.
                              !!  * -3, -4  fatal error in vnls (can not occur here).
      integer :: kuth     = 0 !! input flag to dvstep showing whether h was reduced by the
                              !! driver.  kuth = 1 if h was reduced, = 0 otherwise.
      integer :: l        = 0 !! integer variable, nq + 1, current order plus one.
      integer :: lmax     = 0 !! maxord + 1 (used for dimensioning).
      integer :: lyh      = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: lewt     = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: lacor    = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: lsavf    = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: lwm      = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: liwm     = 0 !! saved integer pointers to segments of rwork and iwork.
      integer :: locjs    = 0 !! a pointer to the saved jacobian, whose storage starts at
                              !! wm(locjs), if jsv = 1.
      integer :: maxord   = 0 !! the maximum order of integration method to be allowed.
      integer :: meth     = 0 !! the method flags.  see mf.
      integer :: miter    = 0 !! the method flags.  see mf.
      integer :: msbj     = 0 !! the maximum number of steps between j evaluations, = 50.
      integer :: mxhnil   = 0 !! saved value of optional input mxhnil.
      integer :: mxstep   = 0 !! saved value of optional input mxstep.
      integer :: n        = 0 !! the number of first-order odes, = neq.
      integer :: newh     = 0 !! saved integer to flag change of h.
      integer :: newq     = 0 !! the method order to be used on the next step.
      integer :: nhnil    = 0 !! saved counter for occurrences of t + h = t.
      integer :: nq       = 0 !! integer variable, the current integration method order.
      integer :: nqnyh    = 0 !! saved value of nq*nyh.
      integer :: nqwait   = 0 !! a counter controlling the frequency of order changes.
                              !! an order change is about to be considered if nqwait = 1.
      integer :: nslj     = 0 !! the number of steps taken as of the last jacobian update.
      integer :: nslp     = 0 !! saved value of nst as of last newton matrix update.
      integer :: nyh      = 0 !! saved value of the initial value of neq.

      ! type declarations formerly in common block dvod02
      real(wp) :: hu  = zero !! the step size in t last used.
      integer :: ncfn = 0 !! number of nonlinear convergence failures so far.
      integer :: netf = 0 !! the number of error test failures of the integrator so far.
      integer :: nfe  = 0 !! the number of f evaluations for the problem so far.
      integer :: nje  = 0 !! the number of jacobian evaluations so far.
      integer :: nlu  = 0 !! the number of matrix lu decompositions so far.
      integer :: nni  = 0 !! number of nonlinear iterations so far.
      integer :: nqu  = 0 !! the method order last used.
      integer :: nst  = 0 !! the number of steps taken for the problem so far.

   end type  dvode_data_t