double precision function dasum	(	integer	N,
		double precision, dimension(*)	DX,
		integer	INCX
	)

DASUM

Purpose:

    DASUM takes the sum of the absolute values.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date

December 2016

Further Details:

     jack dongarra, linpack, 3/11/78.
     modified 3/93 to return if incx .le. 0.
     modified 12/3/93, array(1) declarations changed to array(*)

Definition at line 53 of file dasum.f.

*
*  -- Reference BLAS level1 routine (version 3.7.0) --
*  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     December 2016
*
*     .. Scalar Arguments ..
      INTEGER incx,n
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION dx(*)
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      DOUBLE PRECISION dtemp
      INTEGER i,m,mp1,nincx
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC dabs,mod
*     ..
      dasum = 0.0d0
      dtemp = 0.0d0
      IF (n.LE.0 .OR. incx.LE.0) RETURN
      IF (incx.EQ.1) THEN
*        code for increment equal to 1
*
*
*        clean-up loop
*
         m = mod(n,6)
         IF (m.NE.0) THEN
            DO i = 1,m
               dtemp = dtemp + dabs(dx(i))
            END DO
            IF (n.LT.6) THEN
               dasum = dtemp
               RETURN
            END IF
         END IF
         mp1 = m + 1
         DO i = mp1,n,6
            dtemp = dtemp + dabs(dx(i)) + dabs(dx(i+1)) +
     $              dabs(dx(i+2)) + dabs(dx(i+3)) +
     $              dabs(dx(i+4)) + dabs(dx(i+5))
         END DO
      ELSE
*
*        code for increment not equal to 1
*
         nincx = n*incx
         DO i = 1,nincx,incx
            dtemp = dtemp + dabs(dx(i))
         END DO
      END IF
      dasum = dtemp
      RETURN

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