*> \brief \b DASUM * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX) * * .. Scalar Arguments .. * INTEGER INCX,N * .. * .. Array Arguments .. * DOUBLE PRECISION DX(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DASUM takes the sum of the absolute values. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in] DX *> \verbatim *> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of DX *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \date November 2017 * *> \ingroup double_blas_level1 * *> \par Further Details: * ===================== *> *> \verbatim *> *> 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(*) *> \endverbatim *> * ===================================================================== DOUBLE PRECISION FUNCTION DASUM(N,DX,INCX) * * -- Reference BLAS level1 routine (version 3.8.0) -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * November 2017 * * .. 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 END