Using the Sequential 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.

	5. A storage area and work space array must be provided.
	   It is of type real and the size is 2 * NPTS + SZ_ASI

	

II. PROCEDURES:


  **** Subroutine to select the interpolator type
  *
  *	interpolator_type = clginterp (param)
  *
  *	char	param[ARB]
  *
  *	     The parameter prompt string is sent to the CL and the
  *	routine evaluates the returned string to select one of the
  *	interpolator types given in interpdef.h.  The input string
  *	may be one of the following with possible abbreviations:
  *		nearest
  *		linear
  *		3rd order poly
  *		5th order poly
  ****		cubic spline


  **** 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 set interpolator type.
  *
  *	asiset(coeff,interpolator_type)
  *
  *	real	coeff[ARB]		# work + storage array, dimension
  *					# 2 * NPTS + SZ_ASI
  ****	int	interpolator_type	# see above


  **** Subroutine to fit interpolator to data.
  *
  *	asifit (datain, npts, coeff)
  *
  *	real	datain[ARB]	# data array 
  *	int	npts		# number of points in data array
  ****	real	coeff[ARB]	# work+storage area dim 2*npts + SZ_ASI
  
  
  **** Subroutine to return interpolated value after fitting.  
  *
  *	real asival (x, coeff)
  *	
  *	real	x
  ****	real	coeff[ARB]
  
  
  **** Subroutine to evaluate an ordered sequence of values.
  *
  *	asieva (x, y, n, coeff)
  *
  *	real	x[ARB]		# input array of x values
  *	real	y[ARB]		# output array of interpolated values
  *	int	n		# number of x values
  ****	real	coeff[ARB]
  
  
  **** Subroutine to evaluate derivatives at a point.
  *
  *	asider (x, derivs, nder, coeff)
  *
  *	real	x
  *	real	derivs[ARB]	# output array containing derivatives
  *				# derivs[1] is function value
  *	int	nder		# input:  nder - 1 derivatives are evaluated
  ****	real	coeff[ARB]
  
      
  **** Subroutine to integrate the interpolated data.
  *
  *	real asigrl (a, b, coeff)
  *
  *	real	a		# lower limit
  *	real	b		# upper limit
  ****	real	coeff[ARB]