?getf2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 3/31/2023

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?getf2

Computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

Syntax

call sgetf2( m, n, a, lda, ipiv, info )

call dgetf2( m, n, a, lda, ipiv, info )

call cgetf2( m, n, a, lda, ipiv, info )

call zgetf2( m, n, a, lda, ipiv, info )

Include Files

mkl.fi

Description

The routine computes the LU factorization of a general m-by-n matrix A using partial pivoting with row interchanges. The factorization has the form

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).

Input Parameters

The data types are given for the Fortran interface.

m

INTEGER. The number of rows in the matrix A (m≥ 0).

n

INTEGER. The number of columns in A (n≥ 0).

a

REAL for sgetf2

DOUBLE PRECISION for dgetf2

COMPLEX for cgetf2

DOUBLE COMPLEX for zgetf2.

Array, size (lda,*). Contains the matrix A to be factored. The second dimension of a must be at least max(1, n).

lda

INTEGER. The leading dimension of a; at least max(1, m).

Output Parameters

a

Overwritten by L and U. The unit diagonal elements of L are not stored.

ipiv

INTEGER.

Array, size at least max(1,min(m,n)).

The pivot indices: for 1 ≤ i ≤ n, row i was interchanged with row ipiv(i).

info

INTEGER. If info=0, the execution is successful.

If info = -i, the i-th parameter had an illegal value.

If info = i >0, u_ii is 0. The factorization has been completed, but U is exactly singular. Division by 0 will occur if you use the factor U for solving a system of linear equations.

If info = -1011, memory allocation error occurred.

Parent topic: LAPACK Auxiliary Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?getf2