#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int sgetrf_(integer *m, integer *n, real *a, integer *lda, integer *ipiv, integer *info) { /* -- LAPACK routine (version 3.1) -- Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. November 2006 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 right-looking Level 3 BLAS version of the algorithm. Arguments ========= M (input) INTEGER The number of rows of the matrix A. M >= 0. N (input) INTEGER The number of columns of the matrix A. N >= 0. A (input/output) 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. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,M). IPIV (output) 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). INFO (output) 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. ===================================================================== Test the input parameters. Parameter adjustments */ /* Table of constant values */ static integer c__1 = 1; static integer c_n1 = -1; static real c_b16 = 1.f; static real c_b19 = -1.f; /* System generated locals */ integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5; /* Local variables */ static integer i__, j, jb, nb, iinfo; extern /* Subroutine */ int sgemm_(char *, char *, integer *, integer *, integer *, real *, real *, integer *, real *, integer *, real *, real *, integer *), strsm_(char *, char *, char *, char *, integer *, integer *, real *, real *, integer *, real *, integer *), sgetf2_(integer *, integer *, real *, integer *, integer *, integer *), xerbla_(char *, integer *); extern integer ilaenv_(integer *, char *, char *, integer *, integer *, integer *, integer *, ftnlen, ftnlen); extern /* Subroutine */ int slaswp_(integer *, real *, integer *, integer *, integer *, integer *, integer *); a_dim1 = *lda; a_offset = 1 + a_dim1; a -= a_offset; --ipiv; /* Function Body */ *info = 0; if (*m < 0) { *info = -1; } else if (*n < 0) { *info = -2; } else if (*lda < max(1,*m)) { *info = -4; } if (*info != 0) { i__1 = -(*info); xerbla_("SGETRF", &i__1); return 0; } /* Quick return if possible */ if (*m == 0 || *n == 0) { return 0; } /* Determine the block size for this environment. */ nb = ilaenv_(&c__1, "SGETRF", " ", m, n, &c_n1, &c_n1, (ftnlen)6, (ftnlen)1); if (nb <= 1 || nb >= min(*m,*n)) { /* Use unblocked code. */ sgetf2_(m, n, &a[a_offset], lda, &ipiv[1], info); } else { /* Use blocked code. */ i__1 = min(*m,*n); i__2 = nb; for (j = 1; i__2 < 0 ? j >= i__1 : j <= i__1; j += i__2) { /* Computing MIN */ i__3 = min(*m,*n) - j + 1; jb = min(i__3,nb); /* Factor diagonal and subdiagonal blocks and test for exact singularity. */ i__3 = *m - j + 1; sgetf2_(&i__3, &jb, &a[j + j * a_dim1], lda, &ipiv[j], &iinfo); /* Adjust INFO and the pivot indices. */ if (*info == 0 && iinfo > 0) { *info = iinfo + j - 1; } /* Computing MIN */ i__4 = *m, i__5 = j + jb - 1; i__3 = min(i__4,i__5); for (i__ = j; i__ <= i__3; ++i__) { ipiv[i__] = j - 1 + ipiv[i__]; /* L10: */ } /* Apply interchanges to columns 1:J-1. */ i__3 = j - 1; i__4 = j + jb - 1; slaswp_(&i__3, &a[a_offset], lda, &j, &i__4, &ipiv[1], &c__1); if (j + jb <= *n) { /* Apply interchanges to columns J+JB:N. */ i__3 = *n - j - jb + 1; i__4 = j + jb - 1; slaswp_(&i__3, &a[(j + jb) * a_dim1 + 1], lda, &j, &i__4, & ipiv[1], &c__1); /* Compute block row of U. */ i__3 = *n - j - jb + 1; strsm_("Left", "Lower", "No transpose", "Unit", &jb, &i__3, & c_b16, &a[j + j * a_dim1], lda, &a[j + (j + jb) * a_dim1], lda); if (j + jb <= *m) { /* Update trailing submatrix. */ i__3 = *m - j - jb + 1; i__4 = *n - j - jb + 1; sgemm_("No transpose", "No transpose", &i__3, &i__4, &jb, &c_b19, &a[j + jb + j * a_dim1], lda, &a[j + (j + jb) * a_dim1], lda, &c_b16, &a[j + jb + (j + jb) * a_dim1], lda); } } /* L20: */ } } return 0; /* End of SGETRF */ } /* sgetrf_ */