odr_long_c Subroutine

   subroutine odr_long_c( &
      fcn, &
      n, m, q, np, &
      ldwe, ld2we, &
      ldwd, ld2wd, &
      ldifx, &
      ldstpd, ldscld, &
      lrwork, liwork, &
      beta, y, x, &
      we, wd, &
      ifixb, ifixx, &
      stpb, stpd, &
      sclb, scld, &
      delta, &
      lower, upper, &
      rwork, iwork, &
      job, ndigit, taufac, &
      sstol, partol, maxit, &
      iprint, lunerr, lunrpt, &
      info) bind(C)
   !! "Long-call" wrapper for the `odr` routine including all optional arguments.

      procedure(fcn_tc) :: fcn
         !! User-supplied subroutine for evaluating the model.
      integer(c_int), intent(in) :: n
         !! Number of observations.
      integer(c_int), intent(in) :: m
         !! Number of columns of data in the independent variable.
      integer(c_int), intent(in) :: q
         !! Number of responses per observation.
      integer(c_int), intent(in) :: np
         !! Number of function parameters.
      integer(c_int), intent(in) :: ldwe
         !! Leading dimension of array `we`, `ldwe ∈ {1, n}`.
      integer(c_int), intent(in) :: ld2we
         !! Second dimension of array `we`, `ld2we ∈ {1, q}`.
      integer(c_int), intent(in) :: ldwd
         !! Leading dimension of array `wd`, `ldwd ∈ {1, n}`.
      integer(c_int), intent(in) :: ld2wd
         !! Second dimension of array `wd`, `ld2wd ∈ {1, m}`.
      integer(c_int), intent(in) :: ldifx
         !! Leading dimension of array `ifixx`, `ldifx ∈ {1, n}`.
      integer(c_int), intent(in) :: ldstpd
         !! Leading dimension of array `stpd`, `ldstpd ∈ {1, n}`.
      integer(c_int), intent(in) :: ldscld
         !! Leading dimension of array `scld`, `ldscld ∈ {1, n}`.
      integer(c_int), intent(in) :: lrwork
         !! Length of array `rwork`.
      integer(c_int), intent(in) :: liwork
         !! Length of array `iwork`.
      real(c_double), intent(inout) :: beta(np)
         !! Function parameters.
      real(c_double), intent(in) :: y(n, q)
         !! Dependent variable. Unused when the model is implicit.
      real(c_double), intent(in) :: x(n, m)
         !! Explanatory variable.
      real(c_double), intent(in), optional :: we(ldwe, ld2we, q)
         !! `epsilon` weights.
      real(c_double), intent(in), optional :: wd(ldwd, ld2wd, m)
         !! `delta` weights.
      integer(c_int), intent(in), optional :: ifixb(np)
         !! Values designating whether the elements of `beta` are fixed at their input values or not.
      integer(c_int), intent(in), optional :: ifixx(ldifx, m)
         !! Values designating whether the elements of `x` are fixed at their input values or not.
      real(c_double), intent(in), optional :: stpb(np)
         !! Relative step for computing finite difference derivatives with respect to `beta`.
      real(c_double), intent(in), optional :: stpd(ldstpd, m)
         !! Relative step for computing finite difference derivatives with respect to `delta`.
      real(c_double), intent(in), optional :: sclb(np)
         !! Scaling values for `beta`.
      real(c_double), intent(in), optional :: scld(ldscld, m)
         !! Scaling values for `delta`.
      real(c_double), intent(inout), optional :: delta(n, m)
         !! Error in the `x` data. `Shape: (n, m)`. Initial guess on input and estimated value
         !! on output.
      real(c_double), intent(in), optional :: lower(np)
         !! Lower bound on `beta`.
      real(c_double), intent(in), optional :: upper(np)
         !! Upper bound on `beta`.
      real(c_double), intent(inout), optional :: rwork(lrwork)
         !! Real work space.
      integer(c_int), intent(inout), optional :: iwork(liwork)
         !! Integer work space.
      integer(c_int), intent(in), optional :: job
         !! Variable controlling initialization and computational method.
      integer(c_int), intent(in), optional :: ndigit
         !! Number of accurate digits in the function results, as supplied by the user.
      real(c_double), intent(in), optional :: taufac
         !! Factor used to compute the initial trust region diameter.
      real(c_double), intent(in), optional :: sstol
         !! Sum-of-squares convergence stopping tolerance.
      real(c_double), intent(in), optional :: partol
         !! Parameter convergence stopping tolerance.
      integer(c_int), intent(in), optional :: maxit
         !! Maximum number of iterations allowed.
      integer(c_int), intent(in), optional :: iprint
         !! Print control variable.
      integer(c_int), intent(in), optional :: lunerr
         !! Logical unit number for error messages.
         !!  `0`: No output.
         !!  `6`: Output to standard output.
         !!  `k /= 0,6`: Output to logical unit `k`.
      integer(c_int), intent(in), optional :: lunrpt
         !! Logical unit number for computation reports.
         !!  `0`: No output.
         !!  `6`: Output to standard output.
         !!  `k /= 0,6`: Output to logical unit `k`.
      integer(c_int), intent(out), optional :: info
         !! Variable designating why the computations were stopped.

      call odr(fcn_, n, m, q, np, beta, y, x, &
               we=we, wd=wd, &
               ifixb=ifixb, ifixx=ifixx, &
               delta=delta, &
               lower=lower, upper=upper, &
               job=job, &
               ndigit=ndigit, taufac=taufac, sstol=sstol, partol=partol, maxit=maxit, &
               iprint=iprint, lunerr=lunerr, lunrpt=lunrpt, &
               stpb=stpb, stpd=stpd, &
               sclb=sclb, scld=scld, &
               info=info, &
               rwork=rwork, iwork=iwork)

   contains

      subroutine fcn_(beta, xplusd, ifixb, ifixx, ideval, f, fjacb, fjacd, istop)
         real(c_double), intent(in) :: beta(:)
         real(c_double), intent(in) :: xplusd(:, :)
         integer(c_int), intent(in) :: ifixb(:)
         integer(c_int), intent(in) :: ifixx(:, :)
         integer(c_int), intent(in) :: ideval
         real(c_double), intent(out) :: f(:, :)
         real(c_double), intent(out) :: fjacb(:, :, :)
         real(c_double), intent(out) :: fjacd(:, :, :)
         integer(c_int), intent(out) :: istop

         call fcn(n, m, q, np, ldifx, &
                  beta, xplusd, ifixb, ifixx, ideval, f, fjacb, fjacd, istop)

      end subroutine fcn_

   end subroutine odr_long_c