redhat man page for zdrot

SUBROUTINE ZDROT( N, CX, INCX, CY, INCY, C, S )
    INTEGER INCX, INCY, N
    DOUBLE PRECISION C, S
    COMPLEX*16 CX( * ), CY( * )
    INTEGER I, IX, IY
    COMPLEX*16 CTEMP
    IF( N.LE.0 ) RETURN
    IF( INCX.EQ.1 .AND. INCY.EQ.1 ) GO TO 20
    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
    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