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Annotation of rpl/lapack/lapack/dzsum1.f, revision 1.15

1.11      bertrand    1: *> \brief \b DZSUM1 forms the 1-norm of the complex vector using the true absolute value.
1.8       bertrand    2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
1.15    ! bertrand    5: * Online html documentation available at
        !             6: *            http://www.netlib.org/lapack/explore-html/
1.8       bertrand    7: *
                      8: *> \htmlonly
1.15    ! bertrand    9: *> Download DZSUM1 + dependencies
        !            10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dzsum1.f">
        !            11: *> [TGZ]</a>
        !            12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dzsum1.f">
        !            13: *> [ZIP]</a>
        !            14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dzsum1.f">
1.8       bertrand   15: *> [TXT]</a>
1.15    ! bertrand   16: *> \endhtmlonly
1.8       bertrand   17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
1.15    ! bertrand   22: *
1.8       bertrand   23: *       .. Scalar Arguments ..
                     24: *       INTEGER            INCX, N
                     25: *       ..
                     26: *       .. Array Arguments ..
                     27: *       COMPLEX*16         CX( * )
                     28: *       ..
1.15    ! bertrand   29: *
1.8       bertrand   30: *
                     31: *> \par Purpose:
                     32: *  =============
                     33: *>
                     34: *> \verbatim
                     35: *>
                     36: *> DZSUM1 takes the sum of the absolute values of a complex
                     37: *> vector and returns a double precision result.
                     38: *>
                     39: *> Based on DZASUM from the Level 1 BLAS.
                     40: *> The change is to use the 'genuine' absolute value.
                     41: *> \endverbatim
                     42: *
                     43: *  Arguments:
                     44: *  ==========
                     45: *
                     46: *> \param[in] N
                     47: *> \verbatim
                     48: *>          N is INTEGER
                     49: *>          The number of elements in the vector CX.
                     50: *> \endverbatim
                     51: *>
                     52: *> \param[in] CX
                     53: *> \verbatim
                     54: *>          CX is COMPLEX*16 array, dimension (N)
                     55: *>          The vector whose elements will be summed.
                     56: *> \endverbatim
                     57: *>
                     58: *> \param[in] INCX
                     59: *> \verbatim
                     60: *>          INCX is INTEGER
                     61: *>          The spacing between successive values of CX.  INCX > 0.
                     62: *> \endverbatim
                     63: *
                     64: *  Authors:
                     65: *  ========
                     66: *
1.15    ! bertrand   67: *> \author Univ. of Tennessee
        !            68: *> \author Univ. of California Berkeley
        !            69: *> \author Univ. of Colorado Denver
        !            70: *> \author NAG Ltd.
1.8       bertrand   71: *
1.15    ! bertrand   72: *> \date December 2016
1.8       bertrand   73: *
                     74: *> \ingroup complex16OTHERauxiliary
                     75: *
                     76: *> \par Contributors:
                     77: *  ==================
                     78: *>
                     79: *> Nick Higham for use with ZLACON.
                     80: *
                     81: *  =====================================================================
1.1       bertrand   82:       DOUBLE PRECISION FUNCTION DZSUM1( N, CX, INCX )
                     83: *
1.15    ! bertrand   84: *  -- LAPACK auxiliary routine (version 3.7.0) --
1.1       bertrand   85: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                     86: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.15    ! bertrand   87: *     December 2016
1.1       bertrand   88: *
                     89: *     .. Scalar Arguments ..
                     90:       INTEGER            INCX, N
                     91: *     ..
                     92: *     .. Array Arguments ..
                     93:       COMPLEX*16         CX( * )
                     94: *     ..
                     95: *
                     96: *  =====================================================================
                     97: *
                     98: *     .. Local Scalars ..
                     99:       INTEGER            I, NINCX
                    100:       DOUBLE PRECISION   STEMP
                    101: *     ..
                    102: *     .. Intrinsic Functions ..
                    103:       INTRINSIC          ABS
                    104: *     ..
                    105: *     .. Executable Statements ..
                    106: *
                    107:       DZSUM1 = 0.0D0
                    108:       STEMP = 0.0D0
                    109:       IF( N.LE.0 )
                    110:      $   RETURN
                    111:       IF( INCX.EQ.1 )
                    112:      $   GO TO 20
                    113: *
                    114: *     CODE FOR INCREMENT NOT EQUAL TO 1
                    115: *
                    116:       NINCX = N*INCX
                    117:       DO 10 I = 1, NINCX, INCX
                    118: *
                    119: *        NEXT LINE MODIFIED.
                    120: *
                    121:          STEMP = STEMP + ABS( CX( I ) )
                    122:    10 CONTINUE
                    123:       DZSUM1 = STEMP
                    124:       RETURN
                    125: *
                    126: *     CODE FOR INCREMENT EQUAL TO 1
                    127: *
                    128:    20 CONTINUE
                    129:       DO 30 I = 1, N
                    130: *
                    131: *        NEXT LINE MODIFIED.
                    132: *
                    133:          STEMP = STEMP + ABS( CX( I ) )
                    134:    30 CONTINUE
                    135:       DZSUM1 = STEMP
                    136:       RETURN
                    137: *
                    138: *     End of DZSUM1
                    139: *
                    140:       END