curvefit_lmder_sub Subroutine

  subroutine curvefit_lmder_sub(model_func,model_dfunc,a,xdata,ydata,tol,info)
    interface
       subroutine model_func(x,a,f)
         real(8),dimension(:)       :: x
         real(8),dimension(:)       :: a
         real(8),dimension(size(x)) :: f
       end subroutine model_func
       !
       subroutine model_dfunc(x,a,df)
         real(8),dimension(:)               :: x
         real(8),dimension(:)               :: a
         real(8),dimension(size(x),size(a)) :: df
       end subroutine model_dfunc
    end interface
    real(8),dimension(:)                   :: a
    real(8),dimension(:)                   :: xdata
    real(8),dimension(size(xdata))         :: ydata
    integer                                :: m
    real(8),optional                       :: tol
    integer,optional                       :: info
    real(8)                                :: tol_
    integer                                :: info_
    integer                                :: n
    real(8),dimension(size(xdata))         :: fvec
    real(8),dimension(size(xdata),size(a)) :: fjac
    tol_ = 1.d-15;if(present(tol))tol_=tol
    n=size(a)
    m=size(xdata)
    call lmder1(curvefit_lmder1_sub2sub,m,n,a,fvec,fjac,m,tol_,info_)
    if(present(info))info=info_
  contains
    subroutine curvefit_lmder1_sub2sub(m,n,a,fvec,fjac,ldfjac,iflag)
      integer ::  m
      integer ::  n
      integer ::  ldfjac
      real(8) ::  a(n)
      real(8) ::  fvec(m),fvec_(m)
      real(8) ::  fjac(ldfjac,n)
      integer ::  iflag
      if(iflag==1)then
         call model_func(xdata,a,fvec_)
         fvec = fvec_ - ydata
      elseif(iflag==2)then
         call model_dfunc(xdata,a,fjac)
      endif
      if(iflag<0)stop "CURVEFIT_LMDER1_sub2sub ERROR: iflag < 0 "
    end subroutine curvefit_lmder1_sub2sub
  end subroutine curvefit_lmder_sub