Annotation of rpl/lapack/blas/drot.f, revision 1.7
1.1 bertrand 1: SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
2: * .. Scalar Arguments ..
3: DOUBLE PRECISION C,S
4: INTEGER INCX,INCY,N
5: * ..
6: * .. Array Arguments ..
7: DOUBLE PRECISION DX(*),DY(*)
8: * ..
9: *
10: * Purpose
11: * =======
12: *
13: * DROT applies a plane rotation.
14: *
15: * Further Details
16: * ===============
17: *
18: * jack dongarra, linpack, 3/11/78.
19: * modified 12/3/93, array(1) declarations changed to array(*)
20: *
21: * =====================================================================
22: *
23: * .. Local Scalars ..
24: DOUBLE PRECISION DTEMP
25: INTEGER I,IX,IY
26: * ..
27: IF (N.LE.0) RETURN
1.7 ! bertrand 28: IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
! 29: *
! 30: * code for both increments equal to 1
! 31: *
! 32: DO I = 1,N
! 33: DTEMP = C*DX(I) + S*DY(I)
! 34: DY(I) = C*DY(I) - S*DX(I)
! 35: DX(I) = DTEMP
! 36: END DO
! 37: ELSE
1.1 bertrand 38: *
39: * code for unequal increments or equal increments not equal
40: * to 1
41: *
1.7 ! bertrand 42: IX = 1
! 43: IY = 1
! 44: IF (INCX.LT.0) IX = (-N+1)*INCX + 1
! 45: IF (INCY.LT.0) IY = (-N+1)*INCY + 1
! 46: DO I = 1,N
! 47: DTEMP = C*DX(IX) + S*DY(IY)
! 48: DY(IY) = C*DY(IY) - S*DX(IX)
! 49: DX(IX) = DTEMP
! 50: IX = IX + INCX
! 51: IY = IY + INCY
! 52: END DO
! 53: END IF
1.1 bertrand 54: RETURN
55: END
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