p?amax

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/31/2023

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p?amax

Computes the global index of the element of a distributed vector with maximum absolute value.

Syntax

void psamax (const MKL_INT *n , float *amax , MKL_INT *indx , const float *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx );

void pdamax (const MKL_INT *n , double *amax , MKL_INT *indx , const double *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx );

void pcamax (const MKL_INT *n , MKL_Complex8 *amax , MKL_INT *indx , const MKL_Complex8 *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx );

void pzamax (const MKL_INT *n , MKL_Complex16 *amax , MKL_INT *indx , const MKL_Complex16 *x , const MKL_INT *ix , const MKL_INT *jx , const MKL_INT *descx , const MKL_INT *incx );

Include Files

mkl_pblas.h

Description

The functions p?amax compute global index of the maximum element in absolute value 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) The length of distributed vector sub(x), n≥0.

x

(local)

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) 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) array of dimension 9. The array descriptor of the distributed matrix X.

incx

(global) 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

amax

(global).

Maximum absolute value (magnitude) of elements of the distributed vector only in its scope.

indx

(global) The global index of the maximum element in absolute value of the distributed vector sub(x) only in its scope.

Parent topic: PBLAS Level 1 Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

p?amax