ADAS Subroutine h4fasy

C
      subroutine h4fasy( istdim ,
     &                   x      , xa    , n    , ya    , y     , dy    ,
     &                   c1     , c2    , c3   , c4    ,
     &                   form   , iforms
     &                 )
c-----------------------------------------------------------------------
c
c  **************** fortran77 subroutine: h4spl3.for *******************
c
c  purpose: provide a spline interpolate making use of specified
c           asymptotic behaviour
c
c  calling program: various
c
c  notes: (1) uses labelled common  /espl3/
c
c  input : (i*4)  istdim  = dimensionality for splining arrays
c
c  input : (r*8)  x       = required x-value
c  input : (i*4)  x(i)    = knots
c  input : (r*8)  n       = number of knots
c  
c  input : (r*8)  c1(i,j) = 1st spline coefficient precursor
c  input : (r*8)  c2(i,j) = 2nd spline coefficient precursor
c  input : (r*8)  c3(i,j) = 3rd spline coefficient precursor
c  input : (r*8)  c4(i,j) = 4th spline coefficient precursor
c  input : (r*8)  form    = external function specifying asymptotic forms
c  input : (i*4)  iforms  = index of required form
c
c  output: (r*8)  y=returned y-value
c  output: (r*8)  dy=returned derivative
c
c
c  routines:
c          routine    source    brief description
c          -------------------------------------------------------------
c          h4fspl     adas      
c          i4unit     adas      fetch unit number for output of messages
c
c  author:  Hugh P. Summers, University of Strathclyde
c           JA7.08
c           Tel.: +44 (0)141-548-4196
c
c  date:    24 July 2002
c
c
c  version: 1.1   Hugh Summers  24/07/02
c  modified:      first release
c
c-----------------------------------------------------------------------
      INTEGER             IFORMS,      ISTDIM,      N
      REAL*8              C1(ISTDIM,ISTDIM-1),      C2(ISTDIM,ISTDIM-1)
      REAL*8              C3(ISTDIM,ISTDIM-1),      C4(ISTDIM,ISTDIM-1)
      REAL*8              DY,          X,           XA(ISTDIM),  Y
      REAL*8              YA(ISTDIM)