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Annotation of rpl/lapack/blas/zdrot.f, revision 1.14

1.8       bertrand    1: *> \brief \b ZDROT
                      2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
1.13      bertrand    5: * Online html documentation available at
                      6: *            http://www.netlib.org/lapack/explore-html/
1.8       bertrand    7: *
                      8: *  Definition:
                      9: *  ===========
                     10: *
                     11: *       SUBROUTINE ZDROT( N, CX, INCX, CY, INCY, C, S )
1.13      bertrand   12: *
1.8       bertrand   13: *       .. Scalar Arguments ..
                     14: *       INTEGER            INCX, INCY, N
                     15: *       DOUBLE PRECISION   C, S
                     16: *       ..
                     17: *       .. Array Arguments ..
                     18: *       COMPLEX*16         CX( * ), CY( * )
                     19: *       ..
1.13      bertrand   20: *
1.8       bertrand   21: *
                     22: *> \par Purpose:
                     23: *  =============
                     24: *>
                     25: *> \verbatim
                     26: *>
                     27: *> Applies a plane rotation, where the cos and sin (c and s) are real
                     28: *> and the vectors cx and cy are complex.
                     29: *> jack dongarra, linpack, 3/11/78.
                     30: *> \endverbatim
                     31: *
                     32: *  Arguments:
                     33: *  ==========
                     34: *
                     35: *> \param[in] N
                     36: *> \verbatim
                     37: *>          N is INTEGER
                     38: *>           On entry, N specifies the order of the vectors cx and cy.
                     39: *>           N must be at least zero.
                     40: *> \endverbatim
                     41: *>
                     42: *> \param[in,out] CX
                     43: *> \verbatim
                     44: *>          CX is COMPLEX*16 array, dimension at least
                     45: *>           ( 1 + ( N - 1 )*abs( INCX ) ).
                     46: *>           Before entry, the incremented array CX must contain the n
                     47: *>           element vector cx. On exit, CX is overwritten by the updated
                     48: *>           vector cx.
                     49: *> \endverbatim
                     50: *>
                     51: *> \param[in] INCX
                     52: *> \verbatim
                     53: *>          INCX is INTEGER
                     54: *>           On entry, INCX specifies the increment for the elements of
                     55: *>           CX. INCX must not be zero.
                     56: *> \endverbatim
                     57: *>
                     58: *> \param[in,out] CY
                     59: *> \verbatim
                     60: *>          CY is COMPLEX*16 array, dimension at least
                     61: *>           ( 1 + ( N - 1 )*abs( INCY ) ).
                     62: *>           Before entry, the incremented array CY must contain the n
                     63: *>           element vector cy. On exit, CY is overwritten by the updated
                     64: *>           vector cy.
                     65: *> \endverbatim
                     66: *>
                     67: *> \param[in] INCY
                     68: *> \verbatim
                     69: *>          INCY is INTEGER
                     70: *>           On entry, INCY specifies the increment for the elements of
                     71: *>           CY. INCY must not be zero.
                     72: *> \endverbatim
                     73: *>
                     74: *> \param[in] C
                     75: *> \verbatim
                     76: *>          C is DOUBLE PRECISION
                     77: *>           On entry, C specifies the cosine, cos.
                     78: *> \endverbatim
                     79: *>
                     80: *> \param[in] S
                     81: *> \verbatim
                     82: *>          S is DOUBLE PRECISION
                     83: *>           On entry, S specifies the sine, sin.
                     84: *> \endverbatim
                     85: *
                     86: *  Authors:
                     87: *  ========
                     88: *
1.13      bertrand   89: *> \author Univ. of Tennessee
                     90: *> \author Univ. of California Berkeley
                     91: *> \author Univ. of Colorado Denver
                     92: *> \author NAG Ltd.
1.8       bertrand   93: *
1.13      bertrand   94: *> \date December 2016
1.8       bertrand   95: *
                     96: *> \ingroup complex16_blas_level1
                     97: *
                     98: *  =====================================================================
1.1       bertrand   99:       SUBROUTINE ZDROT( N, CX, INCX, CY, INCY, C, S )
                    100: *
1.13      bertrand  101: *  -- Reference BLAS level1 routine (version 3.7.0) --
1.8       bertrand  102: *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
                    103: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.13      bertrand  104: *     December 2016
1.8       bertrand  105: *
1.1       bertrand  106: *     .. Scalar Arguments ..
                    107:       INTEGER            INCX, INCY, N
                    108:       DOUBLE PRECISION   C, S
                    109: *     ..
                    110: *     .. Array Arguments ..
                    111:       COMPLEX*16         CX( * ), CY( * )
                    112: *     ..
                    113: *
                    114: * =====================================================================
                    115: *
                    116: *     .. Local Scalars ..
                    117:       INTEGER            I, IX, IY
                    118:       COMPLEX*16         CTEMP
                    119: *     ..
                    120: *     .. Executable Statements ..
                    121: *
                    122:       IF( N.LE.0 )
                    123:      $   RETURN
1.7       bertrand  124:       IF( INCX.EQ.1 .AND. INCY.EQ.1 ) THEN
                    125: *
                    126: *        code for both increments equal to 1
                    127: *
                    128:          DO I = 1, N
                    129:             CTEMP = C*CX( I ) + S*CY( I )
                    130:             CY( I ) = C*CY( I ) - S*CX( I )
                    131:             CX( I ) = CTEMP
                    132:          END DO
                    133:       ELSE
1.1       bertrand  134: *
                    135: *        code for unequal increments or equal increments not equal
                    136: *          to 1
                    137: *
1.7       bertrand  138:          IX = 1
                    139:          IY = 1
                    140:          IF( INCX.LT.0 )
                    141:      $      IX = ( -N+1 )*INCX + 1
                    142:          IF( INCY.LT.0 )
                    143:      $      IY = ( -N+1 )*INCY + 1
                    144:          DO I = 1, N
                    145:             CTEMP = C*CX( IX ) + S*CY( IY )
                    146:             CY( IY ) = C*CY( IY ) - S*CX( IX )
                    147:             CX( IX ) = CTEMP
                    148:             IX = IX + INCX
                    149:             IY = IY + INCY
                    150:          END DO
                    151:       END IF
1.1       bertrand  152:       RETURN
                    153:       END