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DOUBLE PRECISION FUNCTION DZNRM2(N,X,INCX)
* .. Scalar Arguments ..
INTEGER INCX,N
* ..
* .. Array Arguments ..
DOUBLE COMPLEX X(*)
* ..
*
* Purpose
* =======
*
* DZNRM2 returns the euclidean norm of a vector via the function
* name, so that
*
* DZNRM2 := sqrt( x**H*x )
*
* Further Details
* ===============
*
* -- This version written on 25-October-1982.
* Modified on 14-October-1993 to inline the call to ZLASSQ.
* Sven Hammarling, Nag Ltd.
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ONE,ZERO
PARAMETER (ONE=1.0D+0,ZERO=0.0D+0)
* ..
* .. Local Scalars ..
DOUBLE PRECISION NORM,SCALE,SSQ,TEMP
INTEGER IX
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS,DBLE,DIMAG,SQRT
* ..
IF (N.LT.1 .OR. INCX.LT.1) THEN
NORM = ZERO
ELSE
SCALE = ZERO
SSQ = ONE
* The following loop is equivalent to this call to the LAPACK
* auxiliary routine:
* CALL ZLASSQ( N, X, INCX, SCALE, SSQ )
*
DO 10 IX = 1,1 + (N-1)*INCX,INCX
IF (DBLE(X(IX)).NE.ZERO) THEN
TEMP = ABS(DBLE(X(IX)))
IF (SCALE.LT.TEMP) THEN
SSQ = ONE + SSQ* (SCALE/TEMP)**2
SCALE = TEMP
ELSE
SSQ = SSQ + (TEMP/SCALE)**2
END IF
END IF
IF (DIMAG(X(IX)).NE.ZERO) THEN
TEMP = ABS(DIMAG(X(IX)))
IF (SCALE.LT.TEMP) THEN
SSQ = ONE + SSQ* (SCALE/TEMP)**2
SCALE = TEMP
ELSE
SSQ = SSQ + (TEMP/SCALE)**2
END IF
END IF
10 CONTINUE
NORM = SCALE*SQRT(SSQ)
END IF
*
DZNRM2 = NORM
RETURN
*
* End of DZNRM2.
*
END
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