dzsum1()

double precision function dzsum1	(	integer	N,
		complex*16, dimension( * )	CX,
		integer	INCX
	)

DZSUM1 forms the 1-norm of the complex vector using the true absolute value.

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Purpose:

 DZSUM1 takes the sum of the absolute values of a complex
 vector and returns a double precision result.

 Based on DZASUM from the Level 1 BLAS.
 The change is to use the 'genuine' absolute value.

Parameters

[in]	N	N is INTEGER The number of elements in the vector CX.
[in]	CX	CX is COMPLEX*16 array, dimension (N) The vector whose elements will be summed.
[in]	INCX	INCX is INTEGER The spacing between successive values of CX. INCX > 0.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date

December 2016

Contributors:

Nick Higham for use with ZLACON.

Definition at line 83 of file dzsum1.f.

*
*  -- LAPACK auxiliary routine (version 3.7.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER            INCX, N
*     ..
*     .. Array Arguments ..
      COMPLEX*16         CX( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      INTEGER            I, NINCX
      DOUBLE PRECISION   STEMP
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs
*     ..
*     .. Executable Statements ..
*
      dzsum1 = 0.0d0
      stemp = 0.0d0
      IF( n.LE.0 )
     $   RETURN
      IF( incx.EQ.1 )
     $   GO TO 20
*
*     CODE FOR INCREMENT NOT EQUAL TO 1
*
      nincx = n*incx
      DO 10 i = 1, nincx, incx
*
*        NEXT LINE MODIFIED.
*
         stemp = stemp + abs( cx( i ) )
   10 CONTINUE
      dzsum1 = stemp
      RETURN
*
*     CODE FOR INCREMENT EQUAL TO 1
*
   20 CONTINUE
      DO 30 i = 1, n
*
*        NEXT LINE MODIFIED.
*
         stemp = stemp + abs( cx( i ) )
   30 CONTINUE
      dzsum1 = stemp
      RETURN
*
*     End of DZSUM1
*