	Using the Random One Dimensional Interpolation Routines
	A Quick Note for Programmers 


I. GENERAL NOTES:

	1. Defines are found in file interpdef.h.  The routines
	   are in library interplib.a.

	2. All pixels are assumed to be good. Except for routine
	   arbpix.

	3. This is for uniformly spaced data -- thus for the i-th
	   data value, y[i], the corresponding x[i] = i by assumption.

	4. All x references are assumed to land in the closed interval
	   1 <= x <= NPTS, where NPTS is the number of points in the
	   data array.  If x is outside this range, the result is
	   not specified.


II. PROCEDURES:


  **** Subroutine to replace INDEF's with interpolated values.
  *
  *	arbpix (datain, n, dataout, interpolator_type)
  *
  *	real	datain[ARB]		# data_in array
  *	int	n			# number of points in data_in
  *	real	dataout[ARB]		# array out, may not be same as
  *					# data_in
  *	int	interpolator_type
  *
  *	    The interpolator type can be set to:
  *
  *		IT_NEAREST		nearest neighbor
  *		IT_LINEAR		linear interpolation
  *		IT_POLY3		interior polynomial 3rd order
  *		IT_POLY5		interior polynomial 5th order
  ****		IT_SPLINE3		cubic natural spline


  **** Subroutine to return interpolated value
  *
  *	real arival (x, datain, n , interpolator_type)
  *	
  *	real	x
  *	real	datain[ARB]		# data array
  *	int	n			# number of points in data array
  ****	int	interpolator_type	# see above
  
  
  **** Subroutine to evaluate derivatives at a point.
  *
  *	arider (x, datain, n, derivs, nder, interpolator_type)
  *
  *	real	x
  *	real	datain[ARB]		# data array
  *	int	n			# number of points in data array
  *	real	derivs[ARB]		# output array containing derivatives
  *					# derivs[1] is function value
  *	int	nder			# input:  nder - 1 derivs are evaluated
  ****	int	interpolator_type	# see above
