p?lauu2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

p?lauu2

Computes the product U*U' or L'*L , where U and L are upper or lower triangular matrices (local unblocked algorithm).

Syntax

call pslauu2 ( uplo , n , a , ia , ja , desca )

call pdlauu2 ( uplo , n , a , ia , ja , desca )

call pclauu2 ( uplo , n , a , ia , ja , desca )

call pzlauu2 ( uplo , n , a , ia , ja , desca )

Include Files

mkl_scalapack.h

Description

pslauu2 pdlauu2 pclauu2 pzlauu2 The p?lauu2 routine function computes the product U*U ‘ or L'*L , where the triangular factor U or L is stored in the upper or lower triangular part of the distributed matrix

sub(A)= A(ia:ia+n-1, ja:ja+n-1) .

If uplo = ‘U’ or ‘u’ , then the upper triangle of the result is stored, overwriting the factor U in sub( A ).

If uplo = ‘L’ or ‘l’ , then the lower triangle of the result is stored, overwriting the factor L in sub( A ).

This is the unblocked form of the algorithm, calling BLAS Level 2 Routines . No communication is performed by this routine function , the matrix to operate on should be strictly local to one process.

Input Parameters

uplo

(global) CHARACTER*1 .

Specifies whether the triangular factor stored in the matrix sub( A ) is upper or lower triangular: = U : upper triangular = L : lower triangular.

n

(global) INTEGER .

The number of rows and columns to be operated on, that is, the order of the triangular factor U or L . n ≥ 0 .

a

(local) REAL for pslauu2 DOUBLE PRECISION for pdlauu2 COMPLEX for pclauu2 COMPLEX*16 for pzlauu2 .

Pointer into the local memory to an array of size (lld_a, LOCc(ja+n-1)) . On entry, the local pieces of the triangular factor U or L .

ia

(global) INTEGER .

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

ja

(global) INTEGER .

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

desca

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

Output Parameters

a: (local) On exit, if uplo = 'U' , the upper triangle of the distributed matrix sub( A ) is overwritten with the upper triangle of the product U*U ‘; if uplo = 'L' , the lower triangle of sub( A ) is overwritten with the lower triangle of the product L ‘* L .

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?lauu2

Syntax

Include Files

Description

Input Parameters

Output Parameters