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Annotation of rpl/lapack/lapack/zrot.f, revision 1.11

1.11    ! bertrand    1: *> \brief \b ZROT applies a plane rotation with real cosine and complex sine to a pair of complex vectors.
1.8       bertrand    2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
                      5: * Online html documentation available at 
                      6: *            http://www.netlib.org/lapack/explore-html/ 
                      7: *
                      8: *> \htmlonly
                      9: *> Download ZROT + dependencies 
                     10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zrot.f"> 
                     11: *> [TGZ]</a> 
                     12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zrot.f"> 
                     13: *> [ZIP]</a> 
                     14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zrot.f"> 
                     15: *> [TXT]</a>
                     16: *> \endhtmlonly 
                     17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       SUBROUTINE ZROT( N, CX, INCX, CY, INCY, C, S )
                     22: * 
                     23: *       .. Scalar Arguments ..
                     24: *       INTEGER            INCX, INCY, N
                     25: *       DOUBLE PRECISION   C
                     26: *       COMPLEX*16         S
                     27: *       ..
                     28: *       .. Array Arguments ..
                     29: *       COMPLEX*16         CX( * ), CY( * )
                     30: *       ..
                     31: *  
                     32: *
                     33: *> \par Purpose:
                     34: *  =============
                     35: *>
                     36: *> \verbatim
                     37: *>
                     38: *> ZROT   applies a plane rotation, where the cos (C) is real and the
                     39: *> sin (S) is complex, and the vectors CX and CY are complex.
                     40: *> \endverbatim
                     41: *
                     42: *  Arguments:
                     43: *  ==========
                     44: *
                     45: *> \param[in] N
                     46: *> \verbatim
                     47: *>          N is INTEGER
                     48: *>          The number of elements in the vectors CX and CY.
                     49: *> \endverbatim
                     50: *>
                     51: *> \param[in,out] CX
                     52: *> \verbatim
                     53: *>          CX is COMPLEX*16 array, dimension (N)
                     54: *>          On input, the vector X.
                     55: *>          On output, CX is overwritten with C*X + S*Y.
                     56: *> \endverbatim
                     57: *>
                     58: *> \param[in] INCX
                     59: *> \verbatim
                     60: *>          INCX is INTEGER
                     61: *>          The increment between successive values of CY.  INCX <> 0.
                     62: *> \endverbatim
                     63: *>
                     64: *> \param[in,out] CY
                     65: *> \verbatim
                     66: *>          CY is COMPLEX*16 array, dimension (N)
                     67: *>          On input, the vector Y.
                     68: *>          On output, CY is overwritten with -CONJG(S)*X + C*Y.
                     69: *> \endverbatim
                     70: *>
                     71: *> \param[in] INCY
                     72: *> \verbatim
                     73: *>          INCY is INTEGER
                     74: *>          The increment between successive values of CY.  INCX <> 0.
                     75: *> \endverbatim
                     76: *>
                     77: *> \param[in] C
                     78: *> \verbatim
                     79: *>          C is DOUBLE PRECISION
                     80: *> \endverbatim
                     81: *>
                     82: *> \param[in] S
                     83: *> \verbatim
                     84: *>          S is COMPLEX*16
                     85: *>          C and S define a rotation
                     86: *>             [  C          S  ]
                     87: *>             [ -conjg(S)   C  ]
                     88: *>          where C*C + S*CONJG(S) = 1.0.
                     89: *> \endverbatim
                     90: *
                     91: *  Authors:
                     92: *  ========
                     93: *
                     94: *> \author Univ. of Tennessee 
                     95: *> \author Univ. of California Berkeley 
                     96: *> \author Univ. of Colorado Denver 
                     97: *> \author NAG Ltd. 
                     98: *
1.11    ! bertrand   99: *> \date September 2012
1.8       bertrand  100: *
                    101: *> \ingroup complex16OTHERauxiliary
                    102: *
                    103: *  =====================================================================
1.1       bertrand  104:       SUBROUTINE ZROT( N, CX, INCX, CY, INCY, C, S )
                    105: *
1.11    ! bertrand  106: *  -- LAPACK auxiliary routine (version 3.4.2) --
1.1       bertrand  107: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                    108: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.11    ! bertrand  109: *     September 2012
1.1       bertrand  110: *
                    111: *     .. Scalar Arguments ..
                    112:       INTEGER            INCX, INCY, N
                    113:       DOUBLE PRECISION   C
                    114:       COMPLEX*16         S
                    115: *     ..
                    116: *     .. Array Arguments ..
                    117:       COMPLEX*16         CX( * ), CY( * )
                    118: *     ..
                    119: *
                    120: * =====================================================================
                    121: *
                    122: *     .. Local Scalars ..
                    123:       INTEGER            I, IX, IY
                    124:       COMPLEX*16         STEMP
                    125: *     ..
                    126: *     .. Intrinsic Functions ..
                    127:       INTRINSIC          DCONJG
                    128: *     ..
                    129: *     .. Executable Statements ..
                    130: *
                    131:       IF( N.LE.0 )
                    132:      $   RETURN
                    133:       IF( INCX.EQ.1 .AND. INCY.EQ.1 )
                    134:      $   GO TO 20
                    135: *
                    136: *     Code for unequal increments or equal increments not equal to 1
                    137: *
                    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 10 I = 1, N
                    145:          STEMP = C*CX( IX ) + S*CY( IY )
                    146:          CY( IY ) = C*CY( IY ) - DCONJG( S )*CX( IX )
                    147:          CX( IX ) = STEMP
                    148:          IX = IX + INCX
                    149:          IY = IY + INCY
                    150:    10 CONTINUE
                    151:       RETURN
                    152: *
                    153: *     Code for both increments equal to 1
                    154: *
                    155:    20 CONTINUE
                    156:       DO 30 I = 1, N
                    157:          STEMP = C*CX( I ) + S*CY( I )
                    158:          CY( I ) = C*CY( I ) - DCONJG( S )*CX( I )
                    159:          CX( I ) = STEMP
                    160:    30 CONTINUE
                    161:       RETURN
                    162:       END