p?getrf

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

p?getrf

Computes the LU factorization of a general m-by-n distributed matrix.

Syntax

call psgetrf ( m , n , a , ia , ja , desca , ipiv , info )

call pdgetrf ( m , n , a , ia , ja , desca , ipiv , info )

call pcgetrf ( m , n , a , ia , ja , desca , ipiv , info )

call pzgetrf ( m , n , a , ia , ja , desca , ipiv , info )

Include Files

mkl_scalapack.h

Description

psgetrf pdgetrf pcgetrf pzgetrf The p?getrf routine function forms the LU factorization of a general m -by- n distributed matrix sub( A ) = A ( ia : ia + m -1, ja : ja + n -1) as

A = P*L*U

where P is a permutation matrix, L is lower triangular with unit diagonal elements (lower trapezoidal if m>n ) and U is upper triangular (upper trapezoidal if m < n ). L and U are stored in sub( A ).

The routine function uses partial pivoting, with row interchanges.

NOTE:

This routine supports the Progress Routine feature. See GUID-E982C8B0-E96D-414B-B263-BABF455963F7.xml#GUID-E982C8B0-E96D-414B-B263-BABF455963F7 for details.

Input Parameters

m

(global) INTEGER . The number of rows in the distributed matrix sub( A ); m≥0 .

n

(global) INTEGER . The number of columns in the distributed matrix sub( A ); n≥0 .

a

(local) REAL for psgetrf DOUBLE PRECISION for pdgetrf COMPLEX for pcgetrf DOUBLE COMPLEX for pzgetrf .

Pointer into the local memory to an array of local size (lld_a, LOCc(ja+n-1)) .

Contains the local pieces of the distributed matrix sub( A ) to be factored.

ia , ja

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

desca

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

Output Parameters

a: Overwritten by local pieces of the factors L and U from the factorization A = P*L*U . The unit diagonal elements of L are not stored.

ipiv

(local) INTEGER Array of size LOCr(m_a)+ mb_a .

Contains the pivoting information: local row i was interchanged with global row ipiv ( i ) . This array is tied to the distributed matrix A .

info

(global) INTEGER .

If info=0 , the execution is successful.

info < 0 : if the i -th argument is an array and the j- th entry had an illegal value, then info = -( i *100+ j ); if the i- th argument is a scalar and had an illegal value, then info = -i .

If info = i > 0, u_{ia+i, ja+j-1} is 0. The factorization has been completed, but the factor U is exactly singular. Division by zero will occur if you use the factor U for solving a system of linear equations.

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?getrf

Syntax

Include Files

Description

Input Parameters

Output Parameters