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Trailing-Edge - PDP-10 Archives - decus_20tap2_198111 - decus/20-0026/dsg13.doc
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SUBROUTINE DSG13

PURPOSE
   TO COMPUTE A VECTOR OF SMOOTHED FUNCTION VALUES GIVEN
   VECTORS OF ARGUMENT VALUES AND CORRESPONDING FUNCTION
   VALUES.

USAGE
   CALL DSG13(X,Y,Z,NDIM,IER)

DESCRIPTION OF PARAMETERS
   X	 -  GIVEN VECTOR OF DOUBLE PRECISION ARGUMENT VALUES
	    (DIMENSION NDIM)
   Y	 -  GIVEN VECTOR OF DOUBLE PRECISION FUNCTION VALUES
	    CORRESPONDING TO X (DIMENSION NDIM)
   Z	 -  RESULTING VECTOR OF DOUBLE PRECISION SMOOTHED
	    FUNCTION VALUES (DIMENSION NDIM)
   NDIM  -  DIMENSION OF VECTORS X,Y,AND Z
   IER	 -  RESULTING ERROR PARAMETER
	    IER = -1  - NDIM IS LESS THAN 3
	    IER =  0  - NO ERROR

REMARKS
   (1)	IF IER=-1 THERE HAS BEEN NO COMPUTATION.
   (2)	 Z CAN HAVE THE SAME STORAGE ALLOCATION AS X OR Y.  IF
	 X OR Y IS DISTINCT FROM Z, THEN IT IS NOT DESTROYED.

SUBROUTINES AND SUBPROGRAMS REQUIRED
   NONE

METHOD
   EXCEPT AT THE ENDPOINTS X(1) AND X(NDIM), EACH SMOOTHED
   VALUE Z(I) IS OBTAINED BY EVALUATING AT X(I) THE LEAST-
   SQUARES POLYNOMIAL OF DEGREE 1 RELEVANT TO THE 3 SUCCESSIVE
   POINTS (X(I+K),Y(I+K)) K = -1,0,1.(SEE HILDEBRAND, F.B.,
   INTRODUCTION  TO NUMERICAL ANALYSIS, MC GRAW-HILL, NEW YORK/
   TORONTO/LONDON, 1956, PP.258-311.)