sqrt13.c

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/* sqrt13.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__2 = 2;
static integer c__1 = 1;
static integer c__0 = 0;

/* Subroutine */ int sqrt13_(integer *scale, integer *m, integer *n, real *a, 
        integer *lda, real *norma, integer *iseed)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1;
    real r__1;

    /* Builtin functions */
    double r_sign(real *, real *);

    /* Local variables */
    integer j, info;
    extern doublereal sasum_(integer *, real *, integer *);
    real dummy[1];
    extern /* Subroutine */ int slabad_(real *, real *);
    extern doublereal slamch_(char *), slange_(char *, integer *, 
            integer *, real *, integer *, real *);
    real bignum;
    extern /* Subroutine */ int slascl_(char *, integer *, integer *, real *, 
            real *, integer *, integer *, real *, integer *, integer *), slarnv_(integer *, integer *, integer *, real *);
    real smlnum;


/*  -- LAPACK test routine (version 3.1) -- */
/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/*     November 2006 */

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  SQRT13 generates a full-rank matrix that may be scaled to have large */
/*  or small norm. */

/*  Arguments */
/*  ========= */

/*  SCALE   (input) INTEGER */
/*          SCALE = 1: normally scaled matrix */
/*          SCALE = 2: matrix scaled up */
/*          SCALE = 3: matrix scaled down */

/*  M       (input) INTEGER */
/*          The number of rows of the matrix A. */

/*  N       (input) INTEGER */
/*          The number of columns of A. */

/*  A       (output) REAL array, dimension (LDA,N) */
/*          The M-by-N matrix A. */

/*  LDA     (input) INTEGER */
/*          The leading dimension of the array A. */

/*  NORMA   (output) REAL */
/*          The one-norm of A. */

/*  ISEED   (input/output) integer array, dimension (4) */
/*          Seed for random number generator */

/*  ===================================================================== */

/*     .. Parameters .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */
/*     .. Local Arrays .. */
/*     .. */
/*     .. Executable Statements .. */

    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --iseed;

    /* Function Body */
    if (*m <= 0 || *n <= 0) {
        return 0;
    }

/*     benign matrix */

    i__1 = *n;
    for (j = 1; j <= i__1; ++j) {
        slarnv_(&c__2, &iseed[1], m, &a[j * a_dim1 + 1]);
        if (j <= *m) {
            r__1 = sasum_(m, &a[j * a_dim1 + 1], &c__1);
            a[j + j * a_dim1] += r_sign(&r__1, &a[j + j * a_dim1]);
        }
/* L10: */
    }

/*     scaled versions */

    if (*scale != 1) {
        *norma = slange_("Max", m, n, &a[a_offset], lda, dummy);
        smlnum = slamch_("Safe minimum");
        bignum = 1.f / smlnum;
        slabad_(&smlnum, &bignum);
        smlnum /= slamch_("Epsilon");
        bignum = 1.f / smlnum;

        if (*scale == 2) {

/*           matrix scaled up */

            slascl_("General", &c__0, &c__0, norma, &bignum, m, n, &a[
                    a_offset], lda, &info);
        } else if (*scale == 3) {

/*           matrix scaled down */

            slascl_("General", &c__0, &c__0, norma, &smlnum, m, n, &a[
                    a_offset], lda, &info);
        }
    }

    *norma = slange_("One-norm", m, n, &a[a_offset], lda, dummy);
    return 0;

/*     End of SQRT13 */

} /* sqrt13_ */