stellinstall/splbrk_8f_source.html

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

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

C

      SUBROUTINE splbrk (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

      real X(N),Y(N),B(N),C(N),D(N)

C

      if(iopt.eq.0) then

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

      else

         call spline_ez1(n, x, y, b, c, d)

      endif

C

      bsave=b(nbrk)

      csave=c(nbrk)

      dsave=d(nbrk)

C

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

C

      b(nbrk)=bsave

      c(nbrk)=csave

      d(nbrk)=dsave

C

      return

      end