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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 3/31/2023

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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

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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