Annotation of rpl/lapack/blas/dasum.f, revision 1.8
1.8 ! bertrand 1: *> \brief \b DASUM
! 2: *
! 3: * =========== DOCUMENTATION ===========
! 4: *
! 5: * Online html documentation available at
! 6: * http://www.netlib.org/lapack/explore-html/
! 7: *
! 8: * Definition:
! 9: * ===========
! 10: *
! 11: * DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX)
! 12: *
! 13: * .. Scalar Arguments ..
! 14: * INTEGER INCX,N
! 15: * ..
! 16: * .. Array Arguments ..
! 17: * DOUBLE PRECISION DX(*)
! 18: * ..
! 19: *
! 20: *
! 21: *> \par Purpose:
! 22: * =============
! 23: *>
! 24: *> \verbatim
! 25: *>
! 26: *> DASUM takes the sum of the absolute values.
! 27: *> \endverbatim
! 28: *
! 29: * Authors:
! 30: * ========
! 31: *
! 32: *> \author Univ. of Tennessee
! 33: *> \author Univ. of California Berkeley
! 34: *> \author Univ. of Colorado Denver
! 35: *> \author NAG Ltd.
! 36: *
! 37: *> \date November 2011
! 38: *
! 39: *> \ingroup double_blas_level1
! 40: *
! 41: *> \par Further Details:
! 42: * =====================
! 43: *>
! 44: *> \verbatim
! 45: *>
! 46: *> jack dongarra, linpack, 3/11/78.
! 47: *> modified 3/93 to return if incx .le. 0.
! 48: *> modified 12/3/93, array(1) declarations changed to array(*)
! 49: *> \endverbatim
! 50: *>
! 51: * =====================================================================
1.1 bertrand 52: DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX)
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: INTEGER INCX,N
61: * ..
62: * .. Array Arguments ..
63: DOUBLE PRECISION DX(*)
64: * ..
65: *
66: * =====================================================================
67: *
68: * .. Local Scalars ..
69: DOUBLE PRECISION DTEMP
70: INTEGER I,M,MP1,NINCX
71: * ..
72: * .. Intrinsic Functions ..
73: INTRINSIC DABS,MOD
74: * ..
75: DASUM = 0.0d0
76: DTEMP = 0.0d0
77: IF (N.LE.0 .OR. INCX.LE.0) RETURN
1.7 bertrand 78: IF (INCX.EQ.1) THEN
79: * code for increment equal to 1
1.1 bertrand 80: *
81: *
1.7 bertrand 82: * clean-up loop
1.1 bertrand 83: *
1.7 bertrand 84: M = MOD(N,6)
85: IF (M.NE.0) THEN
86: DO I = 1,M
87: DTEMP = DTEMP + DABS(DX(I))
88: END DO
89: IF (N.LT.6) THEN
90: DASUM = DTEMP
91: RETURN
92: END IF
93: END IF
94: MP1 = M + 1
95: DO I = MP1,N,6
96: DTEMP = DTEMP + DABS(DX(I)) + DABS(DX(I+1)) +
97: $ DABS(DX(I+2)) + DABS(DX(I+3)) +
98: $ DABS(DX(I+4)) + DABS(DX(I+5))
99: END DO
100: ELSE
1.1 bertrand 101: *
1.7 bertrand 102: * code for increment not equal to 1
1.1 bertrand 103: *
1.7 bertrand 104: NINCX = N*INCX
105: DO I = 1,NINCX,INCX
106: DTEMP = DTEMP + DABS(DX(I))
107: END DO
108: END IF
109: DASUM = DTEMP
1.1 bertrand 110: RETURN
111: END
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