stellinstall/r8splbrk_8f_source.html

C--------------------------------------------------------------------

C  SPLBRK -- make a spline with a break (C0 only) at specified locn

C

      SUBROUTINE r8splbrk (IOPT, N, NBRK, X, Y, B, C, D)

C

C  Spline the whole interval, and then respline a subinterval, saving

C  the endpt coeffs from the original spline.

C

C  Result is a spline that is C2 everywhere except C0 only at one

C  interior break point.

C

C  IOPT=0  use SPLAAN for dy/dx=0 at LHS bc

C  IOPT=1  use SPLINE for standard bc

C

C  N -- no. of data pts

C  NBRK -- break point

C

!============

! idecl:  explicitize implicit INTEGER declarations:

      IMPLICIT NONE

      INTEGER, PARAMETER :: R8=selected_real_kind(12,100)

      INTEGER n,nbrk,iopt

!============

! idecl:  explicitize implicit REAL declarations:

      real*8 bsave,csave,dsave

!============

      real*8 x(n),y(n),b(n),c(n),d(n)

C

      if(iopt.eq.0) then

         call r8splaan(n, x, y, b, c, d)

      else

         call r8spline(n, x, y, b, c, d)

      endif

C

      bsave=b(nbrk)

      csave=c(nbrk)

      dsave=d(nbrk)

C

      call r8nspline(nbrk, x, y, b, c, d)

C

      b(nbrk)=bsave

      c(nbrk)=csave

      d(nbrk)=dsave

C

      return

      end