*DECK ENORM REAL FUNCTION ENORM (N, X) C***BEGIN PROLOGUE ENORM C***SUBSIDIARY C***PURPOSE Subsidiary to SNLS1, SNLS1E, SNSQ and SNSQE C***LIBRARY SLATEC C***TYPE SINGLE 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 REAL FUNCTION ENORM(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 SNLS1, SNLS1E, SNSQ, SNSQE C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C 800301 DATE WRITTEN 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 ENORM