*> \brief \b CROT applies a plane rotation with real cosine and complex sine to a pair of complex vectors. * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * *> \htmlonly *> Download CROT + dependencies *> *> [TGZ] *> *> [ZIP] *> *> [TXT] *> \endhtmlonly * * Definition: * =========== * * SUBROUTINE CROT( N, CX, INCX, CY, INCY, C, S ) * * .. Scalar Arguments .. * INTEGER INCX, INCY, N * REAL C * COMPLEX S * .. * .. Array Arguments .. * COMPLEX CX( * ), CY( * ) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> CROT applies a plane rotation, where the cos (C) is real and the *> sin (S) is complex, and the vectors CX and CY are complex. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> The number of elements in the vectors CX and CY. *> \endverbatim *> *> \param[in,out] CX *> \verbatim *> CX is COMPLEX array, dimension (N) *> On input, the vector X. *> On output, CX is overwritten with C*X + S*Y. *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> The increment between successive values of CX. INCX <> 0. *> \endverbatim *> *> \param[in,out] CY *> \verbatim *> CY is COMPLEX array, dimension (N) *> On input, the vector Y. *> On output, CY is overwritten with -CONJG(S)*X + C*Y. *> \endverbatim *> *> \param[in] INCY *> \verbatim *> INCY is INTEGER *> The increment between successive values of CY. INCX <> 0. *> \endverbatim *> *> \param[in] C *> \verbatim *> C is REAL *> \endverbatim *> *> \param[in] S *> \verbatim *> S is COMPLEX *> C and S define a rotation *> [ C S ] *> [ -conjg(S) C ] *> where C*C + S*CONJG(S) = 1.0. *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup complexOTHERauxiliary * * ===================================================================== SUBROUTINE CROT( N, CX, INCX, CY, INCY, C, S ) * * -- LAPACK auxiliary routine -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX, INCY, N REAL C COMPLEX S * .. * .. Array Arguments .. COMPLEX CX( * ), CY( * ) * .. * * ===================================================================== * * .. Local Scalars .. INTEGER I, IX, IY COMPLEX STEMP * .. * .. Intrinsic Functions .. INTRINSIC CONJG * .. * .. Executable Statements .. * IF( N.LE.0 ) \$ RETURN IF( INCX.EQ.1 .AND. INCY.EQ.1 ) \$ GO TO 20 * * Code for unequal increments or equal increments not equal to 1 * IX = 1 IY = 1 IF( INCX.LT.0 ) \$ IX = ( -N+1 )*INCX + 1 IF( INCY.LT.0 ) \$ IY = ( -N+1 )*INCY + 1 DO 10 I = 1, N STEMP = C*CX( IX ) + S*CY( IY ) CY( IY ) = C*CY( IY ) - CONJG( S )*CX( IX ) CX( IX ) = STEMP IX = IX + INCX IY = IY + INCY 10 CONTINUE RETURN * * Code for both increments equal to 1 * 20 CONTINUE DO 30 I = 1, N STEMP = C*CX( I ) + S*CY( I ) CY( I ) = C*CY( I ) - CONJG( S )*CX( I ) CX( I ) = STEMP 30 CONTINUE RETURN END