LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dgetrf (M, N, A, LDA, IPIV, INFO) 
DGETRF VARIANT: leftlooking Level 3 BLAS version of the algorithm. 
subroutine dgetrf  (  integer  M, 
integer  N,  
double precision, dimension( lda, * )  A,  
integer  LDA,  
integer, dimension( * )  IPIV,  
integer  INFO  
) 
DGETRF VARIANT: leftlooking Level 3 BLAS version of the algorithm.
Purpose:
DGETRF computes an LU factorization of a general MbyN 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 leftlooking 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 DOUBLE PRECISION array, dimension (LDA,N) On entry, the MbyN 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 ith 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 101 of file dgetrf.f.