#include "blaswrap.h" #include "f2c.h" /* Subroutine */ int zgetf2_(integer *m, integer *n, doublecomplex *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 ======= ZGETF2 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 2 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) COMPLEX*16 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 = -k, the k-th argument had an illegal value > 0: if INFO = k, U(k,k) 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 doublecomplex c_b1 = {1.,0.}; static integer c__1 = 1; /* System generated locals */ integer a_dim1, a_offset, i__1, i__2, i__3; doublecomplex z__1; /* Builtin functions */ double z_abs(doublecomplex *); void z_div(doublecomplex *, doublecomplex *, doublecomplex *); /* Local variables */ static integer i__, j, jp; static doublereal sfmin; extern /* Subroutine */ int zscal_(integer *, doublecomplex *, doublecomplex *, integer *), zgeru_(integer *, integer *, doublecomplex *, doublecomplex *, integer *, doublecomplex *, integer *, doublecomplex *, integer *), zswap_(integer *, doublecomplex *, integer *, doublecomplex *, integer *); extern doublereal dlamch_(char *); extern /* Subroutine */ int xerbla_(char *, integer *); extern integer izamax_(integer *, doublecomplex *, 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_("ZGETF2", &i__1); return 0; } /* Quick return if possible */ if (*m == 0 || *n == 0) { return 0; } /* Compute machine safe minimum */ sfmin = dlamch_("S"); i__1 = min(*m,*n); for (j = 1; j <= i__1; ++j) { /* Find pivot and test for singularity. */ i__2 = *m - j + 1; jp = j - 1 + izamax_(&i__2, &a[j + j * a_dim1], &c__1); ipiv[j] = jp; i__2 = jp + j * a_dim1; if (a[i__2].r != 0. || a[i__2].i != 0.) { /* Apply the interchange to columns 1:N. */ if (jp != j) { zswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda); } /* Compute elements J+1:M of J-th column. */ if (j < *m) { if (z_abs(&a[j + j * a_dim1]) >= sfmin) { i__2 = *m - j; z_div(&z__1, &c_b1, &a[j + j * a_dim1]); zscal_(&i__2, &z__1, &a[j + 1 + j * a_dim1], &c__1); } else { i__2 = *m - j; for (i__ = 1; i__ <= i__2; ++i__) { i__3 = j + i__ + j * a_dim1; z_div(&z__1, &a[j + i__ + j * a_dim1], &a[j + j * a_dim1]); a[i__3].r = z__1.r, a[i__3].i = z__1.i; /* L20: */ } } } } else if (*info == 0) { *info = j; } if (j < min(*m,*n)) { /* Update trailing submatrix. */ i__2 = *m - j; i__3 = *n - j; z__1.r = -1., z__1.i = -0.; zgeru_(&i__2, &i__3, &z__1, &a[j + 1 + j * a_dim1], &c__1, &a[j + (j + 1) * a_dim1], lda, &a[j + 1 + (j + 1) * a_dim1], lda) ; } /* L10: */ } return 0; /* End of ZGETF2 */ } /* zgetf2_ */