vsip_dlud_p - Perform LU Decomposition

Core

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6.3.4 vsip_dlud_p - Perform LU Decomposition

int vsip_lud_f(const vsip_lu_f* lud, const vsip_mview_f* A); 
int vsip_clud_f(const vsip_clu_f* lud, const vsip_cmview_f* A);

Description

This function performs LU decomposition of matrix $A$ using the pre-allocated LU decomposition object $lud$ . The decomposition computes:

A =PLU

where:

$P$ is a permutation matrix
$L$ is a unit lower triangular matrix
$U$ is an upper triangular matrix

The function uses partial pivoting for numerical stability. The decomposed factors are stored within the LU decomposition object and can be used for subsequent operations like solving linear systems.

Parameters

const vsip_dlu_p* lud: Pointer to the LU decomposition object created by vsip_lud_create_p .
const vsip_dmview_p* A: Pointer to the $n ×n$ matrix view to be decomposed.

Return Value

Returns 0 on success.
Returns a non-zero value on error (e.g., if the matrix is singular or dimensions don’t match the LU object).

Example

vsip_lu_f *lu_obj; 
vsip_mview_f *matrix_A; 
int result; 
 
// Assuming lu_obj and matrix_A have been properly initialized 
// with matching dimensions 
result = vsip_lud_f(lu_obj, matrix_A); 
 
if (result != 0) { 
    // Handle error (e.g., singular matrix) 
}

Notes

The input matrix $A$ must have full rank.
The input matrix $A$ must have the same dimensions as specified when creating the LU decomposition object.
The contents of matrix $A$ may be overwritten and must not be modified as long as factorization is required.
The decomposed factors $L$ and $U$ are stored within the LU decomposition object and can be accessed through other VSIPL functions.

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