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    1: *> \brief \b DZASUM
    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 DZASUM(N,ZX,INCX)
   12: * 
   13: *       .. Scalar Arguments ..
   14: *       INTEGER INCX,N
   15: *       ..
   16: *       .. Array Arguments ..
   17: *       COMPLEX*16 ZX(*)
   18: *       ..
   19: *  
   20: *
   21: *> \par Purpose:
   22: *  =============
   23: *>
   24: *> \verbatim
   25: *>
   26: *>    DZASUM 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, 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: *  =====================================================================
   52:       DOUBLE PRECISION FUNCTION DZASUM(N,ZX,INCX)
   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: *
   59: *     .. Scalar Arguments ..
   60:       INTEGER INCX,N
   61: *     ..
   62: *     .. Array Arguments ..
   63:       COMPLEX*16 ZX(*)
   64: *     ..
   65: *
   66: *  =====================================================================
   67: *
   68: *     .. Local Scalars ..
   69:       DOUBLE PRECISION STEMP
   70:       INTEGER I,NINCX
   71: *     ..
   72: *     .. External Functions ..
   73:       DOUBLE PRECISION DCABS1
   74:       EXTERNAL DCABS1
   75: *     ..
   76:       DZASUM = 0.0d0
   77:       STEMP = 0.0d0
   78:       IF (N.LE.0 .OR. INCX.LE.0) RETURN
   79:       IF (INCX.EQ.1) THEN
   80: *
   81: *        code for increment equal to 1
   82: *
   83:          DO I = 1,N
   84:             STEMP = STEMP + DCABS1(ZX(I))
   85:          END DO
   86:       ELSE
   87: *
   88: *        code for increment not equal to 1
   89: *
   90:          NINCX = N*INCX
   91:          DO I = 1,NINCX,INCX
   92:             STEMP = STEMP + DCABS1(ZX(I))
   93:          END DO
   94:       END IF
   95:       DZASUM = STEMP
   96:       RETURN
   97:       END