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    1:       SUBROUTINE ZDROT( N, CX, INCX, CY, INCY, C, S )
    2: *
    3: *     .. Scalar Arguments ..
    4:       INTEGER            INCX, INCY, N
    5:       DOUBLE PRECISION   C, S
    6: *     ..
    7: *     .. Array Arguments ..
    8:       COMPLEX*16         CX( * ), CY( * )
    9: *     ..
   10: *
   11: *  Purpose
   12: *  =======
   13: *
   14: *  Applies a plane rotation, where the cos and sin (c and s) are real
   15: *  and the vectors cx and cy are complex.
   16: *  jack dongarra, linpack, 3/11/78.
   17: *
   18: *  Arguments
   19: *  ==========
   20: *
   21: *  N        (input) INTEGER
   22: *           On entry, N specifies the order of the vectors cx and cy.
   23: *           N must be at least zero.
   24: *           Unchanged on exit.
   25: *
   26: *  CX       (input) COMPLEX*16 array, dimension at least
   27: *           ( 1 + ( N - 1 )*abs( INCX ) ).
   28: *           Before entry, the incremented array CX must contain the n
   29: *           element vector cx. On exit, CX is overwritten by the updated
   30: *           vector cx.
   31: *
   32: *  INCX     (input) INTEGER
   33: *           On entry, INCX specifies the increment for the elements of
   34: *           CX. INCX must not be zero.
   35: *           Unchanged on exit.
   36: *
   37: *  CY       (input) COMPLEX*16 array, dimension at least
   38: *           ( 1 + ( N - 1 )*abs( INCY ) ).
   39: *           Before entry, the incremented array CY must contain the n
   40: *           element vector cy. On exit, CY is overwritten by the updated
   41: *           vector cy.
   42: *
   43: *  INCY     (input) INTEGER
   44: *           On entry, INCY specifies the increment for the elements of
   45: *           CY. INCY must not be zero.
   46: *           Unchanged on exit.
   47: *
   48: *  C        (input) DOUBLE PRECISION
   49: *           On entry, C specifies the cosine, cos.
   50: *           Unchanged on exit.
   51: *
   52: *  S        (input) DOUBLE PRECISION
   53: *           On entry, S specifies the sine, sin.
   54: *           Unchanged on exit.
   55: *
   56: * =====================================================================
   57: *
   58: *     .. Local Scalars ..
   59:       INTEGER            I, IX, IY
   60:       COMPLEX*16         CTEMP
   61: *     ..
   62: *     .. Executable Statements ..
   63: *
   64:       IF( N.LE.0 )
   65:      $   RETURN
   66:       IF( INCX.EQ.1 .AND. INCY.EQ.1 ) THEN
   67: *
   68: *        code for both increments equal to 1
   69: *
   70:          DO I = 1, N
   71:             CTEMP = C*CX( I ) + S*CY( I )
   72:             CY( I ) = C*CY( I ) - S*CX( I )
   73:             CX( I ) = CTEMP
   74:          END DO
   75:       ELSE
   76: *
   77: *        code for unequal increments or equal increments not equal
   78: *          to 1
   79: *
   80:          IX = 1
   81:          IY = 1
   82:          IF( INCX.LT.0 )
   83:      $      IX = ( -N+1 )*INCX + 1
   84:          IF( INCY.LT.0 )
   85:      $      IY = ( -N+1 )*INCY + 1
   86:          DO I = 1, N
   87:             CTEMP = C*CX( IX ) + S*CY( IY )
   88:             CY( IY ) = C*CY( IY ) - S*CX( IX )
   89:             CX( IX ) = CTEMP
   90:             IX = IX + INCX
   91:             IY = IY + INCY
   92:          END DO
   93:       END IF
   94:       RETURN
   95:       END