text: #include "f2c.h"
  #include "blaswrap.h"
  
  /* Table of constant values */
  
  static integer c__3 = 3;
  static integer c__1 = 1;
  static real c_b8 = 1.f;
  static real c_b10 = 0.f;
  
  /* Subroutine */ int slarge_(integer *n, real *a, integer *lda, integer *
  	iseed, real *work, integer *info)
  {
      /* System generated locals */
      integer a_dim1, a_offset, i__1;
      real r__1;
  
      /* Builtin functions */
      double r_sign(real *, real *);
  
      /* Local variables */
      integer i__;
      real wa, wb, wn, tau;
      extern /* Subroutine */ int sger_(integer *, integer *, real *, real *, 
  	    integer *, real *, integer *, real *, integer *);
      extern doublereal snrm2_(integer *, real *, integer *);
      extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *), 
  	    sgemv_(char *, integer *, integer *, real *, real *, integer *, 
  	    real *, integer *, real *, real *, integer *), xerbla_(
  	    char *, integer *), slarnv_(integer *, integer *, integer 
  	    *, real *);
  
  
  /*  -- LAPACK auxiliary test routine (version 3.1) */
  /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
  /*     November 2006 */
  
  /*     .. Scalar Arguments .. */
  /*     .. */
  /*     .. Array Arguments .. */
  /*     .. */
  
  /*  Purpose */
  /*  ======= */
  
  /*  SLARGE pre- and post-multiplies a real general n by n matrix A */
  /*  with a random orthogonal matrix: A = U*D*U'. */
  
  /*  Arguments */
  /*  ========= */
  
  /*  N       (input) INTEGER */
  /*          The order of the matrix A.  N >= 0. */
  
  /*  A       (input/output) REAL array, dimension (LDA,N) */
  /*          On entry, the original n by n matrix A. */
  /*          On exit, A is overwritten by U*A*U' for some random */
  /*          orthogonal matrix U. */
  
  /*  LDA     (input) INTEGER */
  /*          The leading dimension of the array A.  LDA >= N. */
  
  /*  ISEED   (input/output) INTEGER array, dimension (4) */
  /*          On entry, the seed of the random number generator; the array */
  /*          elements must be between 0 and 4095, and ISEED(4) must be */
  /*          odd. */
  /*          On exit, the seed is updated. */
  
  /*  WORK    (workspace) REAL array, dimension (2*N) */
  
  /*  INFO    (output) INTEGER */
  /*          = 0: successful exit */
  /*          < 0: if INFO = -i, the i-th argument had an illegal value */
  
  /*  ===================================================================== */
  
  /*     .. Parameters .. */
  /*     .. */
  /*     .. Local Scalars .. */
  /*     .. */
  /*     .. External Subroutines .. */
  /*     .. */
  /*     .. Intrinsic Functions .. */
  /*     .. */
  /*     .. External Functions .. */
  /*     .. */
  /*     .. Executable Statements .. */
  
  /*     Test the input arguments */
  
      /* Parameter adjustments */
      a_dim1 = *lda;
      a_offset = 1 + a_dim1;
      a -= a_offset;
      --iseed;
      --work;
  
      /* Function Body */
      *info = 0;
      if (*n < 0) {
  	*info = -1;
      } else if (*lda < max(1,*n)) {
  	*info = -3;
      }
      if (*info < 0) {
  	i__1 = -(*info);
  	xerbla_("SLARGE", &i__1);
  	return 0;
      }
  
  /*     pre- and post-multiply A by random orthogonal matrix */
  
      for (i__ = *n; i__ >= 1; --i__) {
  
  /*        generate random reflection */
  
  	i__1 = *n - i__ + 1;
  	slarnv_(&c__3, &iseed[1], &i__1, &work[1]);
  	i__1 = *n - i__ + 1;
  	wn = snrm2_(&i__1, &work[1], &c__1);
  	wa = r_sign(&wn, &work[1]);
  	if (wn == 0.f) {
  	    tau = 0.f;
  	} else {
  	    wb = work[1] + wa;
  	    i__1 = *n - i__;
  	    r__1 = 1.f / wb;
  	    sscal_(&i__1, &r__1, &work[2], &c__1);
  	    work[1] = 1.f;
  	    tau = wb / wa;
  	}
  
  /*        multiply A(i:n,1:n) by random reflection from the left */
  
  	i__1 = *n - i__ + 1;
  	sgemv_("Transpose", &i__1, n, &c_b8, &a[i__ + a_dim1], lda, &work[1], 
  		&c__1, &c_b10, &work[*n + 1], &c__1);
  	i__1 = *n - i__ + 1;
  	r__1 = -tau;
  	sger_(&i__1, n, &r__1, &work[1], &c__1, &work[*n + 1], &c__1, &a[i__ 
  		+ a_dim1], lda);
  
  /*        multiply A(1:n,i:n) by random reflection from the right */
  
  	i__1 = *n - i__ + 1;
  	sgemv_("No transpose", n, &i__1, &c_b8, &a[i__ * a_dim1 + 1], lda, &
  		work[1], &c__1, &c_b10, &work[*n + 1], &c__1);
  	i__1 = *n - i__ + 1;
  	r__1 = -tau;
  	sger_(n, &i__1, &r__1, &work[*n + 1], &c__1, &work[1], &c__1, &a[i__ *
  		 a_dim1 + 1], lda);
  /* L10: */
      }
      return 0;
  
  /*     End of SLARGE */
  
  } /* slarge_ */
  