p?asum

Computes the sum of magnitudes of elements of a distributed vector.

Syntax

call psasum(n, asum, x, ix, jx, descx, incx)

call pscasum(n, asum, x, ix, jx, descx, incx)

call pdasum(n, asum, x, ix, jx, descx, incx)

call pdzasum(n, asum, x, ix, jx, descx, incx)

Include Files

The C interfaces for this function are specified in the mkl_pblas.h include file.

Description

The functions p?asum compute the sum of the magnitudes of elements of a distributed vector sub(x),

where sub(x) denotes X(ix, jx:jx+n-1) if incx=m_x, and X(ix: ix+n-1, jx) if incx= 1.

Input Parameters

n

(global) INTEGER. The length of distributed vector sub(x), n≥0.

x

(local) REAL for psasum

DOUBLE PRECISION for pdasum

COMPLEX for pscasum

DOUBLE COMPLEX for pdzasum

Array, DIMENSION (jx-1)*m_x + ix+(n-1)*abs(incx)).

This array contains the entries of the distributed vector sub(x).

ix, jx

(global) INTEGER. The row and column indices in the distributed matrix X indicating the first row and the first column of the submatrix sub(X), respectively.

descx

(global and local) INTEGER array of dimension 8. The array descriptor of the distributed matrix X.

incx

(global) INTEGER. Specifies the increment for the elements of sub(x). Only two values are supported, namely 1 and m_x. incx must not be zero.

Output Parameters

asum

(local) REAL for psasum and pscasum.

DOUBLE PRECISION for pdasum and pdzasum

Contains the sum of magnitudes of elements of the distributed vector only in its scope.