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Annotation of rpl/lapack/lapack/zlacrt.f, revision 1.8

1.8     ! bertrand    1: *> \brief \b ZLACRT
        !             2: *
        !             3: *  =========== DOCUMENTATION ===========
        !             4: *
        !             5: * Online html documentation available at 
        !             6: *            http://www.netlib.org/lapack/explore-html/ 
        !             7: *
        !             8: *> \htmlonly
        !             9: *> Download ZLACRT + dependencies 
        !            10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zlacrt.f"> 
        !            11: *> [TGZ]</a> 
        !            12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zlacrt.f"> 
        !            13: *> [ZIP]</a> 
        !            14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zlacrt.f"> 
        !            15: *> [TXT]</a>
        !            16: *> \endhtmlonly 
        !            17: *
        !            18: *  Definition:
        !            19: *  ===========
        !            20: *
        !            21: *       SUBROUTINE ZLACRT( N, CX, INCX, CY, INCY, C, S )
        !            22: * 
        !            23: *       .. Scalar Arguments ..
        !            24: *       INTEGER            INCX, INCY, N
        !            25: *       COMPLEX*16         C, S
        !            26: *       ..
        !            27: *       .. Array Arguments ..
        !            28: *       COMPLEX*16         CX( * ), CY( * )
        !            29: *       ..
        !            30: *  
        !            31: *
        !            32: *> \par Purpose:
        !            33: *  =============
        !            34: *>
        !            35: *> \verbatim
        !            36: *>
        !            37: *> ZLACRT performs the operation
        !            38: *>
        !            39: *>    (  c  s )( x )  ==> ( x )
        !            40: *>    ( -s  c )( y )      ( y )
        !            41: *>
        !            42: *> where c and s are complex and the vectors x and y are complex.
        !            43: *> \endverbatim
        !            44: *
        !            45: *  Arguments:
        !            46: *  ==========
        !            47: *
        !            48: *> \param[in] N
        !            49: *> \verbatim
        !            50: *>          N is INTEGER
        !            51: *>          The number of elements in the vectors CX and CY.
        !            52: *> \endverbatim
        !            53: *>
        !            54: *> \param[in,out] CX
        !            55: *> \verbatim
        !            56: *>          CX is COMPLEX*16 array, dimension (N)
        !            57: *>          On input, the vector x.
        !            58: *>          On output, CX is overwritten with c*x + s*y.
        !            59: *> \endverbatim
        !            60: *>
        !            61: *> \param[in] INCX
        !            62: *> \verbatim
        !            63: *>          INCX is INTEGER
        !            64: *>          The increment between successive values of CX.  INCX <> 0.
        !            65: *> \endverbatim
        !            66: *>
        !            67: *> \param[in,out] CY
        !            68: *> \verbatim
        !            69: *>          CY is COMPLEX*16 array, dimension (N)
        !            70: *>          On input, the vector y.
        !            71: *>          On output, CY is overwritten with -s*x + c*y.
        !            72: *> \endverbatim
        !            73: *>
        !            74: *> \param[in] INCY
        !            75: *> \verbatim
        !            76: *>          INCY is INTEGER
        !            77: *>          The increment between successive values of CY.  INCY <> 0.
        !            78: *> \endverbatim
        !            79: *>
        !            80: *> \param[in] C
        !            81: *> \verbatim
        !            82: *>          C is COMPLEX*16
        !            83: *> \endverbatim
        !            84: *>
        !            85: *> \param[in] S
        !            86: *> \verbatim
        !            87: *>          S is COMPLEX*16
        !            88: *>          C and S define the matrix
        !            89: *>             [  C   S  ].
        !            90: *>             [ -S   C  ]
        !            91: *> \endverbatim
        !            92: *
        !            93: *  Authors:
        !            94: *  ========
        !            95: *
        !            96: *> \author Univ. of Tennessee 
        !            97: *> \author Univ. of California Berkeley 
        !            98: *> \author Univ. of Colorado Denver 
        !            99: *> \author NAG Ltd. 
        !           100: *
        !           101: *> \date November 2011
        !           102: *
        !           103: *> \ingroup complex16OTHERauxiliary
        !           104: *
        !           105: *  =====================================================================
1.1       bertrand  106:       SUBROUTINE ZLACRT( N, CX, INCX, CY, INCY, C, S )
                    107: *
1.8     ! bertrand  108: *  -- LAPACK auxiliary routine (version 3.4.0) --
1.1       bertrand  109: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                    110: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.8     ! bertrand  111: *     November 2011
1.1       bertrand  112: *
                    113: *     .. Scalar Arguments ..
                    114:       INTEGER            INCX, INCY, N
                    115:       COMPLEX*16         C, S
                    116: *     ..
                    117: *     .. Array Arguments ..
                    118:       COMPLEX*16         CX( * ), CY( * )
                    119: *     ..
                    120: *
                    121: * =====================================================================
                    122: *
                    123: *     .. Local Scalars ..
                    124:       INTEGER            I, IX, IY
                    125:       COMPLEX*16         CTEMP
                    126: *     ..
                    127: *     .. Executable Statements ..
                    128: *
                    129:       IF( N.LE.0 )
                    130:      $   RETURN
                    131:       IF( INCX.EQ.1 .AND. INCY.EQ.1 )
                    132:      $   GO TO 20
                    133: *
                    134: *     Code for unequal increments or equal increments not equal to 1
                    135: *
                    136:       IX = 1
                    137:       IY = 1
                    138:       IF( INCX.LT.0 )
                    139:      $   IX = ( -N+1 )*INCX + 1
                    140:       IF( INCY.LT.0 )
                    141:      $   IY = ( -N+1 )*INCY + 1
                    142:       DO 10 I = 1, N
                    143:          CTEMP = C*CX( IX ) + S*CY( IY )
                    144:          CY( IY ) = C*CY( IY ) - S*CX( IX )
                    145:          CX( IX ) = CTEMP
                    146:          IX = IX + INCX
                    147:          IY = IY + INCY
                    148:    10 CONTINUE
                    149:       RETURN
                    150: *
                    151: *     Code for both increments equal to 1
                    152: *
                    153:    20 CONTINUE
                    154:       DO 30 I = 1, N
                    155:          CTEMP = C*CX( I ) + S*CY( I )
                    156:          CY( I ) = C*CY( I ) - S*CX( I )
                    157:          CX( I ) = CTEMP
                    158:    30 CONTINUE
                    159:       RETURN
                    160:       END