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138 lines
3.2 KiB
138 lines
3.2 KiB
2 years ago
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*> \brief \b DZSUM1 forms the 1-norm of the complex vector using the true absolute value.
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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*> \htmlonly
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*> Download DZSUM1 + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dzsum1.f">
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*> [TGZ]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dzsum1.f">
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*> [ZIP]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dzsum1.f">
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*> [TXT]</a>
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*> \endhtmlonly
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*
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* Definition:
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* ===========
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*
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* DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
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*
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* .. Scalar Arguments ..
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* INTEGER INCX, N
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* ..
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* .. Array Arguments ..
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* COMPLEX*16 CX( * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*>
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*> DZSUM1 takes the sum of the absolute values of a complex
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*> vector and returns a double precision result.
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*>
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*> Based on DZASUM from the Level 1 BLAS.
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*> The change is to use the 'genuine' absolute value.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The number of elements in the vector CX.
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*> \endverbatim
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*>
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*> \param[in] CX
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*> \verbatim
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*> CX is COMPLEX*16 array, dimension (N)
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*> The vector whose elements will be summed.
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*> \endverbatim
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*>
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*> \param[in] INCX
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*> \verbatim
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*> INCX is INTEGER
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*> The spacing between successive values of CX. INCX > 0.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \ingroup complex16OTHERauxiliary
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*
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*> \par Contributors:
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* ==================
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*>
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*> Nick Higham for use with ZLACON.
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*
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* =====================================================================
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DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
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*
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* -- LAPACK auxiliary routine --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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*
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* .. Scalar Arguments ..
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INTEGER INCX, N
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* ..
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* .. Array Arguments ..
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COMPLEX*16 CX( * )
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* ..
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*
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* =====================================================================
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*
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* .. Local Scalars ..
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INTEGER I, NINCX
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DOUBLE PRECISION STEMP
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS
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* ..
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* .. Executable Statements ..
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*
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DZSUM1 = 0.0D0
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STEMP = 0.0D0
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IF( N.LE.0 )
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$ RETURN
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IF( INCX.EQ.1 )
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$ GO TO 20
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*
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* CODE FOR INCREMENT NOT EQUAL TO 1
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*
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NINCX = N*INCX
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DO 10 I = 1, NINCX, INCX
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*
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* NEXT LINE MODIFIED.
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*
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STEMP = STEMP + ABS( CX( I ) )
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10 CONTINUE
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DZSUM1 = STEMP
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RETURN
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*
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* CODE FOR INCREMENT EQUAL TO 1
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*
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20 CONTINUE
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DO 30 I = 1, N
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*
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* NEXT LINE MODIFIED.
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*
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STEMP = STEMP + ABS( CX( I ) )
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30 CONTINUE
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DZSUM1 = STEMP
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RETURN
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*
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* End of DZSUM1
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*
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END
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