comparison ext/clapack/src/dgetf2.c @ 202:45330e0d2819 clapack-included

Add the CLAPACK and CBLAS/F2C-BLAS files we use

+/* dgetf2.f -- translated by f2c (version 20061008).
+   You must link the resulting object file with libf2c:
+	on Microsoft Windows system, link with libf2c.lib;
+	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
+	or, if you install libf2c.a in a standard place, with -lf2c -lm
+	-- in that order, at the end of the command line, as in
+		cc *.o -lf2c -lm
+	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
+
+		http://www.netlib.org/f2c/libf2c.zip
+*/
+
+#include "f2c.h"
+#include "blaswrap.h"
+
+/* Table of constant values */
+
+static integer c__1 = 1;
+static doublereal c_b8 = -1.;
+
+/* Subroutine */ int dgetf2_(integer *m, integer *n, doublereal *a, integer *
+	lda, integer *ipiv, integer *info)
+{
+    /* System generated locals */
+    integer a_dim1, a_offset, i__1, i__2, i__3;
+    doublereal d__1;
+
+    /* Local variables */
+    integer i__, j, jp;
+    extern /* Subroutine */ int dger_(integer *, integer *, doublereal *, 
+	    doublereal *, integer *, doublereal *, integer *, doublereal *, 
+	    integer *), dscal_(integer *, doublereal *, doublereal *, integer 
+	    *);
+    doublereal sfmin;
+    extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *, 
+	    doublereal *, integer *);
+    extern doublereal dlamch_(char *);
+    extern integer idamax_(integer *, doublereal *, integer *);
+    extern /* Subroutine */ int xerbla_(char *, integer *);
+
+
+/*  -- LAPACK routine (version 3.2) -- */
+/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/*     November 2006 */
+
+/*     .. Scalar Arguments .. */
+/*     .. */
+/*     .. Array Arguments .. */
+/*     .. */
+
+/*  Purpose */
+/*  ======= */
+
+/*  DGETF2 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) DOUBLE PRECISION 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. */
+
+/*  ===================================================================== */
+
+/*     .. Parameters .. */
+/*     .. */
+/*     .. Local Scalars .. */
+/*     .. */
+/*     .. External Functions .. */
+/*     .. */
+/*     .. External Subroutines .. */
+/*     .. */
+/*     .. Intrinsic Functions .. */
+/*     .. */
+/*     .. Executable Statements .. */
+
+/*     Test the input parameters. */
+
+    /* Parameter adjustments */
+    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_("DGETF2", &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 + idamax_(&i__2, &a[j + j * a_dim1], &c__1);
+	ipiv[j] = jp;
+	if (a[jp + j * a_dim1] != 0.) {
+
+/*           Apply the interchange to columns 1:N. */
+
+	    if (jp != j) {
+		dswap_(n, &a[j + a_dim1], lda, &a[jp + a_dim1], lda);
+	    }
+
+/*           Compute elements J+1:M of J-th column. */
+
+	    if (j < *m) {
+		if ((d__1 = a[j + j * a_dim1], abs(d__1)) >= sfmin) {
+		    i__2 = *m - j;
+		    d__1 = 1. / a[j + j * a_dim1];
+		    dscal_(&i__2, &d__1, &a[j + 1 + j * a_dim1], &c__1);
+		} else {
+		    i__2 = *m - j;
+		    for (i__ = 1; i__ <= i__2; ++i__) {
+			a[j + i__ + j * a_dim1] /= a[j + j * a_dim1];
+/* L20: */
+		    }
+		}
+	    }
+
+	} else if (*info == 0) {
+
+	    *info = j;
+	}
+
+	if (j < min(*m,*n)) {
+
+/*           Update trailing submatrix. */
+
+	    i__2 = *m - j;
+	    i__3 = *n - j;
+	    dger_(&i__2, &i__3, &c_b8, &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 DGETF2 */
+
+} /* dgetf2_ */