?getrfnp_batch

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?getrfnp_batch_strided

Computes the LU factorization, without pivoting, of a group of general m-by-n matrices that are stored at a constant stride from each other in a contiguous block of memory.

Syntax

call sgetrfnp_batch_strided ( m , n , A , lda , stride_a , batch_size , info )

call dgetrfnp_batch_strided ( m , n , A , lda , stride_a , batch_size , info )

call cgetrfnp_batch_strided ( m , n , A , lda , stride_a , batch_size , info )

call zgetrfnp_batch_strided ( m , n , A , lda , stride_a , batch_size , info )

Include Files

mkl.fi

Description

The ?getrfnp_batch_strided routines are similar to the ?getrfnp counterparts, but instead compute the LU factorization for a group of general m -by- n matrices.

All matrices A have the same parameters (matrix size, leading dimension) and are stored at constant stride_a from each other in a single block of memory. The operation is defined as

for i = 0 … batch_size-1
     A(i) is a matrix at offset i * stride_a from A
     A(i) :=  L(i) * U(i)
end for

where L(i) is lower triangular with unit diagonal elements (lower trapezoidal if m > n ) and U(i) is upper triangular (upper trapezoidal if m < n ). The routine does not perform any pivoting.

Input Parameters

m

INTEGER . The number of rows in the A matrices: m ≥ 0.

n

INTEGER . The number of columns in the A(i) matrices: n ≥ 0.

A: REAL for sgetrfnp_batch_strided DOUBLE PRECISION for dgetrfnp_batch_strided COMPLEX for cgetrfnp_batch_strided DOUBLE COMPLEX for zgetrfnp_batch_strided The A array of size at least stride_a * batch_size holding the A(i) matrices.

lda

INTEGER . Specifies the leading dimension of the A(i) matrices; lda ≥ max(1, m ).

stride_a: INTEGER . Stride between two consecutive A(i) matrices; stride_a ≥ lda * n .
batch_size: INTEGER . Number of A(i) matrices to be factorized. Must be at least 0.

Output Parameters

A: Array holding the LU-factored A(i) matrices. Each matrix is overwritten by their respective L(i) and U(i) factors. The unit diagonal elements of L are not stored.

info

INTEGER. Array of size at least batch_size , which reports the factorization status for each matrix:

If info(i) = 0, the execution is successful for A(i) .
If info(i) = - j , the j -th parameter had an illegal value for A(i) .
If info(i) = j , the j -th diagonal element of U(i) is 0. The factorization has been completed, but U(i) is exactly singular. Division by 0 will occur if you use the factor U(i) for solving a system of linear equations.

After calling this routine with m = n , you can call the following:

?getrsnp_batch_strided (Solves a group of systems of linear equations, each with an LU-factored square coefficient matrix and multiple right hand sides.)

to solve systems of linear equations of the form

\[A_i X_i = B_i, \quad A_i^T X_i = B_i, \quad \text{or} \quad A_i^H X_i = B_i\]

with the group of LU-factored matrices.

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