denorm.f
DOUBLE PRECISION FUNCTION DENORM (N, X)
C***BEGIN PROLOGUE DENORM
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Warning: this routine is not intended to be user-callable.
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C***SUBSIDIARY
C***PURPOSE Subsidiary to DNSQ and DNSQE
C***LIBRARY SLATEC
C***TYPE DOUBLE PRECISION (ENORM-S, DENORM-D)
C***AUTHOR (UNKNOWN)
C***DESCRIPTION
C
C Given an N-vector X, this function calculates the
C Euclidean norm of X.
C
C The Euclidean norm is computed by accumulating the sum of
C squares in three different sums. The sums of squares for the
C small and large components are scaled so that no overflows
C occur. Non-destructive underflows are permitted. Underflows
C and overflows do not occur in the computation of the unscaled
C sum of squares for the intermediate components.
C The definitions of small, intermediate and large components
C depend on two constants, RDWARF and RGIANT. The main
C restrictions on these constants are that RDWARF**2 not
C underflow and RGIANT**2 not overflow. The constants
C given here are suitable for every known computer.
C
C The function statement is
C
C DOUBLE PRECISION FUNCTION DENORM(N,X)
C
C where
C
C N is a positive integer input variable.
C
C X is an input array of length N.
C
C***SEE ALSO DNSQ, DNSQE
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 800301 DATE WRITTEN
C 890531 Changed all specific intrinsics to generic. (WRB)
C 890831 Modified array declarations. (WRB)
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900326 Removed duplicate information from DESCRIPTION section.
C (WRB)
C 900328 Added TYPE section. (WRB)
C***END PROLOGUE DENORM