p?dot

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

Download PDF

ID 766686

Date 12/16/2022

Version

Public

A newer version of this document is available. Customers should click here to go to the newest version.

Visible to Intel only — GUID: GUID-F0992C6B-2DC3-4B3F-A5B2-00F0641DE3B8

View Details

p?dot

Computes the dot product of two distributed real vectors.

Syntax

call psdot(n, dot, x, ix, jx, descx, incx, y, iy, jy, descy, incy)

call pddot(n, dot, x, ix, jx, descx, incx, y, iy, jy, descy, incy)

Include Files

mkl_pblas.h

Description

The ?dot functions compute the dot product dot of two distributed real vectors defined as

dot  = sub(x)'*sub(y)

where sub(x) and sub(y) are n-element distributed vectors.

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

sub(y) denotes Y(iy, jy:jy+n-1) if incy=m_y, and Y(iy: iy+n-1, jy) if incy= 1.

Input Parameters

n

(global) INTEGER. The length of distributed vectors, n≥0.

x

(local) REAL for psdot

DOUBLE PRECISION for pddot

Array, size (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 9. 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.

y

(local)REAL for psdot

DOUBLE PRECISION for pddot

Array, size (jy-1)*m_y + iy+(n-1)*abs(incy)).

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

iy, jy

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

descy

(global and local) INTEGER array of dimension 9. The array descriptor of the distributed matrix Y.

incy

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

Output Parameters

dot

(local) REAL for psdot

DOUBLE PRECISION for pddot

Dot product of sub(x) and sub(y) only in their scope.

Parent topic: PBLAS Level 1 Routines

Select Your Language

Using Intel.com Search

Quick Links

Recent Searches

Advanced Search

Only search in

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?dot