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Annotation of rpl/lapack/blas/zdrot.f, revision 1.15

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: *
1.15    ! bertrand   11: *       SUBROUTINE ZDROT( N, ZX, INCX, ZY, 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 ..
1.15    ! bertrand   18: *       COMPLEX*16         ZX( * ), ZY( * )
1.8       bertrand   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: *>
1.15    ! bertrand   42: *> \param[in,out] ZX
1.8       bertrand   43: *> \verbatim
1.15    ! bertrand   44: *>          ZX is COMPLEX*16 array, dimension at least
1.8       bertrand   45: *>           ( 1 + ( N - 1 )*abs( INCX ) ).
1.15    ! bertrand   46: *>           Before entry, the incremented array ZX must contain the n
        !            47: *>           element vector cx. On exit, ZX is overwritten by the updated
1.8       bertrand   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
1.15    ! bertrand   55: *>           ZX. INCX must not be zero.
1.8       bertrand   56: *> \endverbatim
                     57: *>
1.15    ! bertrand   58: *> \param[in,out] ZY
1.8       bertrand   59: *> \verbatim
1.15    ! bertrand   60: *>          ZY is COMPLEX*16 array, dimension at least
1.8       bertrand   61: *>           ( 1 + ( N - 1 )*abs( INCY ) ).
1.15    ! bertrand   62: *>           Before entry, the incremented array ZY must contain the n
        !            63: *>           element vector cy. On exit, ZY is overwritten by the updated
1.8       bertrand   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
1.15    ! bertrand   71: *>           ZY. INCY must not be zero.
1.8       bertrand   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: *
                     94: *> \ingroup complex16_blas_level1
                     95: *
                     96: *  =====================================================================
1.15    ! bertrand   97:       SUBROUTINE ZDROT( N, ZX, INCX, ZY, INCY, C, S )
1.1       bertrand   98: *
1.15    ! bertrand   99: *  -- Reference BLAS level1 routine --
1.8       bertrand  100: *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
                    101: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                    102: *
1.1       bertrand  103: *     .. Scalar Arguments ..
                    104:       INTEGER            INCX, INCY, N
                    105:       DOUBLE PRECISION   C, S
                    106: *     ..
                    107: *     .. Array Arguments ..
1.15    ! bertrand  108:       COMPLEX*16         ZX( * ), ZY( * )
1.1       bertrand  109: *     ..
                    110: *
                    111: * =====================================================================
                    112: *
                    113: *     .. Local Scalars ..
                    114:       INTEGER            I, IX, IY
                    115:       COMPLEX*16         CTEMP
                    116: *     ..
                    117: *     .. Executable Statements ..
                    118: *
                    119:       IF( N.LE.0 )
                    120:      $   RETURN
1.7       bertrand  121:       IF( INCX.EQ.1 .AND. INCY.EQ.1 ) THEN
                    122: *
                    123: *        code for both increments equal to 1
                    124: *
                    125:          DO I = 1, N
1.15    ! bertrand  126:             CTEMP = C*ZX( I ) + S*ZY( I )
        !           127:             ZY( I ) = C*ZY( I ) - S*ZX( I )
        !           128:             ZX( I ) = CTEMP
1.7       bertrand  129:          END DO
                    130:       ELSE
1.1       bertrand  131: *
                    132: *        code for unequal increments or equal increments not equal
                    133: *          to 1
                    134: *
1.7       bertrand  135:          IX = 1
                    136:          IY = 1
                    137:          IF( INCX.LT.0 )
                    138:      $      IX = ( -N+1 )*INCX + 1
                    139:          IF( INCY.LT.0 )
                    140:      $      IY = ( -N+1 )*INCY + 1
                    141:          DO I = 1, N
1.15    ! bertrand  142:             CTEMP = C*ZX( IX ) + S*ZY( IY )
        !           143:             ZY( IY ) = C*ZY( IY ) - S*ZX( IX )
        !           144:             ZX( IX ) = CTEMP
1.7       bertrand  145:             IX = IX + INCX
                    146:             IY = IY + INCY
                    147:          END DO
                    148:       END IF
1.1       bertrand  149:       RETURN
1.15    ! bertrand  150: *
        !           151: *     End of ZDROT
        !           152: *
1.1       bertrand  153:       END