1SGETRF(1)                LAPACK routine (version 3.2)                SGETRF(1)
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NAME

6       SGETRF  -  computes  an  LU  factorization of a general M-by-N matrix A
7       using partial pivoting with row interchanges
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SYNOPSIS

10       SUBROUTINE SGETRF( M, N, A, LDA, IPIV, INFO )
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12           INTEGER        INFO, LDA, M, N
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14           INTEGER        IPIV( * )
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16           REAL           A( LDA, * )
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PURPOSE

19       SGETRF computes an LU factorization of a general M-by-N matrix A  using
20       partial pivoting with row interchanges.  The factorization has the form
21          A = P * L * U
22       where P is a permutation matrix, L is lower triangular with unit diago‐
23       nal elements (lower trapezoidal if m > n), and U  is  upper  triangular
24       (upper trapezoidal if m < n).
25       This is the right-looking Level 3 BLAS version of the algorithm.
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ARGUMENTS

28       M       (input) INTEGER
29               The number of rows of the matrix A.  M >= 0.
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31       N       (input) INTEGER
32               The number of columns of the matrix A.  N >= 0.
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34       A       (input/output) REAL array, dimension (LDA,N)
35               On  entry, the M-by-N matrix to be factored.  On exit, the fac‐
36               tors L and U from the factorization A = P*L*U; the unit  diago‐
37               nal elements of L are not stored.
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39       LDA     (input) INTEGER
40               The leading dimension of the array A.  LDA >= max(1,M).
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42       IPIV    (output) INTEGER array, dimension (min(M,N))
43               The  pivot indices; for 1 <= i <= min(M,N), row i of the matrix
44               was interchanged with row IPIV(i).
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46       INFO    (output) INTEGER
47               = 0:  successful exit
48               < 0:  if INFO = -i, the i-th argument had an illegal value
49               > 0:  if INFO = i, U(i,i) is exactly  zero.  The  factorization
50               has  been  completed, but the factor U is exactly singular, and
51               division by zero will occur if it is used to solve a system  of
52               equations.
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56 LAPACK routine (version 3.2)    November 2008                       SGETRF(1)
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