LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
subroutine sgetrf | ( | integer | M, |
integer | N, | ||
real, dimension( lda, * ) | A, | ||
integer | LDA, | ||
integer, dimension( * ) | IPIV, | ||
integer | INFO | ||
) |
SGETRF VARIANT: Crout Level 3 BLAS version of the algorithm.
Purpose:
SGETRF computes an 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). This is the Crout Level 3 BLAS version of the algorithm.
[in] | M | M is INTEGER The number of rows of the matrix A. M >= 0. |
[in] | N | N is INTEGER The number of columns of the matrix A. N >= 0. |
[in,out] | A | A is REAL array, dimension (LDA,N) On entry, the M-by-N matrix to be factored. On exit, the factors L and U from the factorization A = P*L*U; the unit diagonal elements of L are not stored. |
[in] | LDA | LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). |
[out] | IPIV | IPIV is INTEGER array, dimension (min(M,N)) The pivot indices; for 1 <= i <= min(M,N), row i of the matrix was interchanged with row IPIV(i). |
[out] | INFO | INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it is used to solve a system of equations. |
Definition at line 102 of file sgetrf.f.