Annotation of rpl/lapack/blas/drot.f, revision 1.8
1.8 ! bertrand 1: *> \brief \b DROT
! 2: *
! 3: * =========== DOCUMENTATION ===========
! 4: *
! 5: * Online html documentation available at
! 6: * http://www.netlib.org/lapack/explore-html/
! 7: *
! 8: * Definition:
! 9: * ===========
! 10: *
! 11: * SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
! 12: *
! 13: * .. Scalar Arguments ..
! 14: * DOUBLE PRECISION C,S
! 15: * INTEGER INCX,INCY,N
! 16: * ..
! 17: * .. Array Arguments ..
! 18: * DOUBLE PRECISION DX(*),DY(*)
! 19: * ..
! 20: *
! 21: *
! 22: *> \par Purpose:
! 23: * =============
! 24: *>
! 25: *> \verbatim
! 26: *>
! 27: *> DROT applies a plane rotation.
! 28: *> \endverbatim
! 29: *
! 30: * Authors:
! 31: * ========
! 32: *
! 33: *> \author Univ. of Tennessee
! 34: *> \author Univ. of California Berkeley
! 35: *> \author Univ. of Colorado Denver
! 36: *> \author NAG Ltd.
! 37: *
! 38: *> \date November 2011
! 39: *
! 40: *> \ingroup double_blas_level1
! 41: *
! 42: *> \par Further Details:
! 43: * =====================
! 44: *>
! 45: *> \verbatim
! 46: *>
! 47: *> jack dongarra, linpack, 3/11/78.
! 48: *> modified 12/3/93, array(1) declarations changed to array(*)
! 49: *> \endverbatim
! 50: *>
! 51: * =====================================================================
1.1 bertrand 52: SUBROUTINE DROT(N,DX,INCX,DY,INCY,C,S)
1.8 ! bertrand 53: *
! 54: * -- Reference BLAS level1 routine (version 3.4.0) --
! 55: * -- Reference BLAS is a software package provided by Univ. of Tennessee, --
! 56: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 57: * November 2011
! 58: *
1.1 bertrand 59: * .. Scalar Arguments ..
60: DOUBLE PRECISION C,S
61: INTEGER INCX,INCY,N
62: * ..
63: * .. Array Arguments ..
64: DOUBLE PRECISION DX(*),DY(*)
65: * ..
66: *
67: * =====================================================================
68: *
69: * .. Local Scalars ..
70: DOUBLE PRECISION DTEMP
71: INTEGER I,IX,IY
72: * ..
73: IF (N.LE.0) RETURN
1.7 bertrand 74: IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
75: *
76: * code for both increments equal to 1
77: *
78: DO I = 1,N
79: DTEMP = C*DX(I) + S*DY(I)
80: DY(I) = C*DY(I) - S*DX(I)
81: DX(I) = DTEMP
82: END DO
83: ELSE
1.1 bertrand 84: *
85: * code for unequal increments or equal increments not equal
86: * to 1
87: *
1.7 bertrand 88: IX = 1
89: IY = 1
90: IF (INCX.LT.0) IX = (-N+1)*INCX + 1
91: IF (INCY.LT.0) IY = (-N+1)*INCY + 1
92: DO I = 1,N
93: DTEMP = C*DX(IX) + S*DY(IY)
94: DY(IY) = C*DY(IY) - S*DX(IX)
95: DX(IX) = DTEMP
96: IX = IX + INCX
97: IY = IY + INCY
98: END DO
99: END IF
1.1 bertrand 100: RETURN
101: END
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