*> \brief \b DZASUM * * =========== DOCUMENTATION =========== * * Online html documentation available at * http://www.netlib.org/lapack/explore-html/ * * Definition: * =========== * * DOUBLE PRECISION FUNCTION DZASUM(N,ZX,INCX) * * .. Scalar Arguments .. * INTEGER INCX,N * .. * .. Array Arguments .. * COMPLEX*16 ZX(*) * .. * * *> \par Purpose: * ============= *> *> \verbatim *> *> DZASUM takes the sum of the (|Re(.)| + |Im(.)|)'s of a complex vector and *> returns a double precision result. *> \endverbatim * * Arguments: * ========== * *> \param[in] N *> \verbatim *> N is INTEGER *> number of elements in input vector(s) *> \endverbatim *> *> \param[in,out] ZX *> \verbatim *> ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) *> \endverbatim *> *> \param[in] INCX *> \verbatim *> INCX is INTEGER *> storage spacing between elements of ZX *> \endverbatim * * Authors: * ======== * *> \author Univ. of Tennessee *> \author Univ. of California Berkeley *> \author Univ. of Colorado Denver *> \author NAG Ltd. * *> \ingroup double_blas_level1 * *> \par Further Details: * ===================== *> *> \verbatim *> *> jack dongarra, 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 DZASUM(N,ZX,INCX) * * -- Reference BLAS level1 routine -- * -- Reference BLAS is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * * .. Scalar Arguments .. INTEGER INCX,N * .. * .. Array Arguments .. COMPLEX*16 ZX(*) * .. * * ===================================================================== * * .. Local Scalars .. DOUBLE PRECISION STEMP INTEGER I,NINCX * .. * .. External Functions .. DOUBLE PRECISION DCABS1 EXTERNAL DCABS1 * .. DZASUM = 0.0d0 STEMP = 0.0d0 IF (N.LE.0 .OR. INCX.LE.0) RETURN IF (INCX.EQ.1) THEN * * code for increment equal to 1 * DO I = 1,N STEMP = STEMP + DCABS1(ZX(I)) END DO ELSE * * code for increment not equal to 1 * NINCX = N*INCX DO I = 1,NINCX,INCX STEMP = STEMP + DCABS1(ZX(I)) END DO END IF DZASUM = STEMP RETURN * * End of DZASUM * END