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lapack/SRC/scsum1.f
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FortranFixed

*> \brief \b SCSUM1 forms the 1-norm of the complex vector using the true absolute value.
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download SCSUM1 + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/scsum1.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/scsum1.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/scsum1.f">
*> [TXT]</a>
*> \endhtmlonly
*
* Definition:
* ===========
*
* REAL FUNCTION SCSUM1( N, CX, INCX )
*
* .. Scalar Arguments ..
* INTEGER INCX, N
* ..
* .. Array Arguments ..
* COMPLEX CX( * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> SCSUM1 takes the sum of the absolute values of a complex
*> vector and returns a single precision result.
*>
*> Based on SCASUM from the Level 1 BLAS.
*> The change is to use the 'genuine' absolute value.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> The number of elements in the vector CX.
*> \endverbatim
*>
*> \param[in] CX
*> \verbatim
*> CX is COMPLEX array, dimension (N)
*> The vector whose elements will be summed.
*> \endverbatim
*>
*> \param[in] INCX
*> \verbatim
*> INCX is INTEGER
*> The spacing between successive values of CX. INCX > 0.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \ingroup complexOTHERauxiliary
*
*> \par Contributors:
* ==================
*>
*> Nick Higham for use with CLACON.
*
* =====================================================================
REAL FUNCTION SCSUM1( N, CX, INCX )
*
* -- LAPACK auxiliary routine --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*
* .. Scalar Arguments ..
INTEGER INCX, N
* ..
* .. Array Arguments ..
COMPLEX CX( * )
* ..
*
* =====================================================================
*
* .. Local Scalars ..
INTEGER I, NINCX
REAL STEMP
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS
* ..
* .. Executable Statements ..
*
SCSUM1 = 0.0E0
STEMP = 0.0E0
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
SCSUM1 = 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
SCSUM1 = STEMP
RETURN
*
* End of SCSUM1
*
END