p?max1

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/31/2023

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Public

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p?max1

Finds the index of the element whose real part has maximum absolute value (similar to the Level 1 PBLAS p?amax, but using the absolute value to the real part).

Syntax

void pcmax1 (MKL_INT *n , MKL_Complex8 *amax , MKL_INT *indx , MKL_Complex8 *x , MKL_INT *ix , MKL_INT *jx , MKL_INT *descx , MKL_INT *incx );

void pzmax1 (MKL_INT *n , MKL_Complex16 *amax , MKL_INT *indx , MKL_Complex16 *x , MKL_INT *ix , MKL_INT *jx , MKL_INT *descx , MKL_INT *incx );

Include Files

mkl_scalapack.h

Description

The p?max1function computes the global index of the maximum element in absolute value of a distributed vector sub(X). The global index is returned in indx and the value is returned in amax, where sub(X) denotes X(ix:ix+n-1, jx) if incx = 1, X(ix, jx:jx+n-1) if incx = m_x.

Input Parameters

n

(global). The number of components of the distributed vector sub(X). n ≥ 0.

x

(local)

Pointer into the local memory to an array of size lld_x * LOCc(jx+n-1). On entry this array contains the local pieces of the distributed vector sub(X).

ix

(global) The row index in the global matrix X indicating the first row of sub(X).

jx

(global) The column index in the global matrix X indicating the first column of sub(X).

descx

(global and local) Array of size dlen_. The array descriptor for the distributed matrix X.

incx

(global).The global increment for the elements of X. Only two values of incx are supported in this version, namely 1 and m_x. incx must not be zero.

Output Parameters

amax: (global output).The absolute value of the largest entry of the distributed vector sub(X) only in the scope of sub(X).
indx: (global output).The global index of the element of the distributed vector sub(X) whose real part has maximum absolute value.

Parent topic: ScaLAPACK Auxiliary Routines

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p?max1

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