*> \brief \b DNRM2
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*  Definition:
*  ===========
*
*       DOUBLE PRECISION FUNCTION DNRM2(N,X,INCX)
* 
*       .. Scalar Arguments ..
*       INTEGER INCX,N
*       ..
*       .. Array Arguments ..
*       DOUBLE PRECISION X(*)
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> DNRM2 returns the euclidean norm of a vector via the function
*> name, so that
*>
*>    DNRM2 := sqrt( x'*x )
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date November 2011
*
*> \ingroup double_blas_level1
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>  -- This version written on 25-October-1982.
*>     Modified on 14-October-1993 to inline the call to DLASSQ.
*>     Sven Hammarling, Nag Ltd.
*> \endverbatim
*>
*  =====================================================================
      DOUBLE PRECISION FUNCTION GAL_DNRM2(N,X,INCX)
*
*  -- Reference BLAS level1 routine (version 3.4.0) --
*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2011
*
*     .. Scalar Arguments ..
      INTEGER INCX,N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION X(*)
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION ONE,ZERO
      PARAMETER (ONE=1.0D+0,ZERO=0.0D+0)
*     ..
*     .. Local Scalars ..
      DOUBLE PRECISION ABSXI,NORM,SCALE,SSQ
      INTEGER IX
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC ABS,SQRT
*     ..
      IF(N.LT.1.OR.INCX.LT.1)THEN
      NORM=ZERO
      ELSE IF(N.EQ.1)THEN
      NORM=ABS(X(1))
      ELSE 
      SCALE=ZERO
      SSQ=ONE
*        The following loop is equivalent to this call to the LAPACK
*        auxiliary routine:
*        CALL DLASSQ( N, X, INCX, SCALE, SSQ )
*
      DO 10IX=1,1+(N-1)*INCX,INCX
      IF(X(IX).NE.ZERO)THEN
      ABSXI=ABS(X(IX))
      IF(SCALE.LT.ABSXI)THEN
      SSQ=ONE+SSQ*(SCALE/ABSXI)**2
      SCALE=ABSXI
      ELSE 
      SSQ=SSQ+(ABSXI/SCALE)**2
      END IF
      END IF
   10 CONTINUE
      NORM=SCALE*SQRT(SSQ)
      END IF
*
      GAL_DNRM2=NORM
      RETURN
*
*     End of DNRM2.
*
      END 
