SUBROUTINE CLACRT( N, CX, INCX, CY, INCY, C, S ) * * -- LAPACK auxiliary routine (version 3.2) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * November 2006 * * .. Scalar Arguments .. INTEGER INCX, INCY, N COMPLEX C, S * .. * .. Array Arguments .. COMPLEX CX( * ), CY( * ) * .. * * Purpose * ======= * * CLACRT performs the operation * * ( c s )( x ) ==> ( x ) * ( -s c )( y ) ( y ) * * where c and s are complex and the vectors x and y are complex. * * Arguments * ========= * * N (input) INTEGER * The number of elements in the vectors CX and CY. * * CX (input/output) COMPLEX array, dimension (N) * On input, the vector x. * On output, CX is overwritten with c*x + s*y. * * INCX (input) INTEGER * The increment between successive values of CX. INCX <> 0. * * CY (input/output) COMPLEX array, dimension (N) * On input, the vector y. * On output, CY is overwritten with -s*x + c*y. * * INCY (input) INTEGER * The increment between successive values of CY. INCY <> 0. * * C (input) COMPLEX * S (input) COMPLEX * C and S define the matrix * [ C S ]. * [ -S C ] * * ===================================================================== * * .. Local Scalars .. INTEGER I, IX, IY COMPLEX CTEMP * .. * .. 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 CTEMP = C*CX( IX ) + S*CY( IY ) CY( IY ) = C*CY( IY ) - S*CX( IX ) CX( IX ) = CTEMP IX = IX + INCX IY = IY + INCY 10 CONTINUE RETURN * * Code for both increments equal to 1 * 20 CONTINUE DO 30 I = 1, N CTEMP = C*CX( I ) + S*CY( I ) CY( I ) = C*CY( I ) - S*CX( I ) CX( I ) = CTEMP 30 CONTINUE RETURN END