dvnorm.f

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      DOUBLE PRECISION FUNCTION dvnorm (N, V, W)
C***BEGIN PROLOGUE  DVNORM
C***SUBSIDIARY
C***PURPOSE  Weighted root-mean-square vector norm.
C***TYPE      DOUBLE PRECISION (SVNORM-S, DVNORM-D)
C***AUTHOR  Hindmarsh, Alan C., (LLNL)
C***DESCRIPTION
C
C  This function routine computes the weighted root-mean-square norm
C  of the vector of length N contained in the array V, with weights
C  contained in the array W of length N:
C    DVNORM = SQRT( (1/N) * SUM( V(i)*W(i) )**2 )
C
C***SEE ALSO  DLSODE
C***ROUTINES CALLED  (NONE)
C***REVISION HISTORY  (YYMMDD)
C   791129  DATE WRITTEN
C   890501  Modified prologue to SLATEC/LDOC format.  (FNF)
C   890503  Minor cosmetic changes.  (FNF)
C   930809  Renamed to allow single/double precision versions. (ACH)
C***END PROLOGUE  DVNORM
C**End
      INTEGER n,   i
      DOUBLE PRECISION v, w,   sum
      dimension v(n), w(n)
C
C***FIRST EXECUTABLE STATEMENT  DVNORM
      sum = 0.0d0
      DO 10 i = 1,n
 10     sum = sum + (v(i)*w(i))**2
      dvnorm = sqrt(sum/n)
      RETURN
C----------------------- END OF FUNCTION DVNORM ------------------------
      END