pderrasum()

subroutine pderrasum	(	double precision	errbnd,
		integer	n,
		double precision	usclr,
		double precision, dimension( * )	x,
		integer	incx,
		double precision	prec
	)

Definition at line 3163 of file pdblas1tst.f.

*
*  -- PBLAS test routine (version 2.0) --
*     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
*     and University of California, Berkeley.
*     April 1, 1998
*
*     .. Scalar Arguments ..
      INTEGER            INCX, N
      DOUBLE PRECISION   ERRBND, PREC, USCLR
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   X( * )
*     ..
*
*  Purpose
*  =======
*
*  PDERRASUM  serially computes the sum of absolute values of the vector
*  X and returns a scaled relative acceptable error bound on the result.
*
*  Arguments
*  =========
*
*  ERRBND  (global output) DOUBLE PRECISION
*          On exit, ERRBND  specifies a scaled relative acceptable error
*          bound. In this case the error bound is just the absolute  sum
*          multiplied  by  a constant proportional to the machine preci-
*          sion.
*
*  N       (global input) INTEGER
*          On entry, N specifies the length of the vector operand.
*
*  USCLR   (global output) DOUBLE PRECISION
*          On exit, USCLR  specifies  the  sum of absolute values of the
*          vector X.
*
*  X       (global input) DOUBLE PRECISION array
*          On   entry,   X   is   an   array   of   dimension  at  least
*          ( 1 + ( n - 1 )*abs( INCX ) ).  Before  entry,  the incremen-
*          ted array X must contain the vector x.
*
*  INCX    (global input) INTEGER.
*          On entry, INCX specifies the increment for the elements of X.
*          INCX must not be zero.
*
*  PREC    (global input) DOUBLE PRECISION
*          On entry, PREC specifies the machine precision.
*
*  -- Written on April 1, 1998 by
*     Antoine Petitet, University  of  Tennessee, Knoxville 37996, USA.
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   TWO, ZERO
      parameter( two = 2.0d+0, zero = 0.0d+0 )
*     ..
*     .. Local Scalars ..
      INTEGER            IX
      DOUBLE PRECISION   ADDBND
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs
*     ..
*     .. Executable Statements ..
*
      ix = 1
      usclr = zero
      addbnd = two * two * two * prec
*
      DO 10 ix = 1, 1 + ( n - 1 )*incx, incx
         usclr = usclr + abs( x( ix ) )
   10 CONTINUE
*
      errbnd = addbnd * usclr
*
      RETURN
*
*     End of PDERRASUM
*

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