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Annotation of rpl/lapack/lapack/zlacrt.f, revision 1.14

1.11      bertrand    1: *> \brief \b ZLACRT performs a linear transformation of 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 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: *
1.11      bertrand  101: *> \date September 2012
1.8       bertrand  102: *
                    103: *> \ingroup complex16OTHERauxiliary
                    104: *
                    105: *  =====================================================================
1.1       bertrand  106:       SUBROUTINE ZLACRT( N, CX, INCX, CY, INCY, C, S )
                    107: *
1.11      bertrand  108: *  -- LAPACK auxiliary routine (version 3.4.2) --
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..--
1.11      bertrand  111: *     September 2012
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