SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S) * .. Scalar Arguments .. DOUBLE PRECISION C,S INTEGER INCX,INCY,N * .. * .. Array Arguments .. DOUBLE PRECISION DX(*),DY(*) * .. * * Purpose * ======= * * DROT applies a plane rotation. * * Further Details * =============== * * jack dongarra, linpack, 3/11/78. * modified 12/3/93, array(1) declarations changed to array(*) * * ===================================================================== * * .. Local Scalars .. DOUBLE PRECISION DTEMP INTEGER I,IX,IY * .. 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 DTEMP = C*DX(IX) + S*DY(IY) DY(IY) = C*DY(IY) - S*DX(IX) DX(IX) = DTEMP IX = IX + INCX IY = IY + INCY 10 CONTINUE RETURN * * code for both increments equal to 1 * 20 DO 30 I = 1,N DTEMP = C*DX(I) + S*DY(I) DY(I) = C*DY(I) - S*DX(I) DX(I) = DTEMP 30 CONTINUE RETURN END