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decuslib20-02
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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.)