Annotation of rpl/lapack/lapack/zrot.f, revision 1.8
1.8 ! bertrand 1: *> \brief \b ZROT
! 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: *
! 99: *> \date November 2011
! 100: *
! 101: *> \ingroup complex16OTHERauxiliary
! 102: *
! 103: * =====================================================================
1.1 bertrand 104: SUBROUTINE ZROT( N, CX, INCX, CY, INCY, C, S )
105: *
1.8 ! bertrand 106: * -- LAPACK auxiliary routine (version 3.4.0) --
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..--
1.8 ! bertrand 109: * November 2011
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
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