text: /* Copyright (c) 1992-2008 The University of Tennessee.  All rights reserved.
   * See file COPYING in this directory for details. */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include "f2c.h"
  #include "hypre_lapack.h"
  
  /* Subroutine */ integer dorgtr_(const char *uplo, integer *n, doublereal *a, integer *
  	lda, doublereal *tau, doublereal *work, integer *lwork, integer *info)
  {
  /*  -- LAPACK routine (version 3.0) --   
         Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
         Courant Institute, Argonne National Lab, and Rice University   
         June 30, 1999   
  
  
      Purpose   
      =======   
  
      DORGTR generates a real orthogonal matrix Q which is defined as the   
      product of n-1 elementary reflectors of order N, as returned by   
      DSYTRD:   
  
      if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),   
  
      if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).   
  
      Arguments   
      =========   
  
      UPLO    (input) CHARACTER*1   
              = 'U': Upper triangle of A contains elementary reflectors   
                     from DSYTRD;   
              = 'L': Lower triangle of A contains elementary reflectors   
                     from DSYTRD.   
  
      N       (input) INTEGER   
              The order of the matrix Q. N >= 0.   
  
      A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)   
              On entry, the vectors which define the elementary reflectors,   
              as returned by DSYTRD.   
              On exit, the N-by-N orthogonal matrix Q.   
  
      LDA     (input) INTEGER   
              The leading dimension of the array A. LDA >= max(1,N).   
  
      TAU     (input) DOUBLE PRECISION array, dimension (N-1)   
              TAU(i) must contain the scalar factor of the elementary   
              reflector H(i), as returned by DSYTRD.   
  
      WORK    (workspace/output) DOUBLE PRECISION array, dimension (LWORK)   
              On exit, if INFO = 0, WORK(1) returns the optimal LWORK.   
  
      LWORK   (input) INTEGER   
              The dimension of the array WORK. LWORK >= max(1,N-1).   
              For optimum performance LWORK >= (N-1)*NB, where NB is   
              the optimal blocksize.   
  
              If LWORK = -1, then a workspace query is assumed; the routine   
              only calculates the optimal size of the WORK array, returns   
              this value as the first entry of the WORK array, and no error   
              message related to LWORK is issued by XERBLA.   
  
      INFO    (output) INTEGER   
              = 0:  successful exit   
              < 0:  if INFO = -i, the i-th argument had an illegal value   
  
      =====================================================================   
  
  
         Test the input arguments   
  
         Parameter adjustments */
      /* Table of constant values */
      static integer c__1 = 1;
      static integer c_n1 = -1;
      
      /* System generated locals */
      integer a_dim1, a_offset, i__1, i__2, i__3;
      /* Local variables */
      static integer i__, j;
      extern logical lsame_(const char *,const char *);
      static integer iinfo;
      static logical upper;
      static integer nb;
      extern /* Subroutine */ integer xerbla_(const char *, integer *);
      extern integer ilaenv_(integer *,const char *,const char *, integer *, integer *, 
  	    integer *, integer *, ftnlen, ftnlen);
      extern /* Subroutine */ integer dorgql_(integer *, integer *, integer *, 
  	    doublereal *, integer *, doublereal *, doublereal *, integer *, 
  	    integer *), dorgqr_(integer *, integer *, integer *, doublereal *,
  	     integer *, doublereal *, doublereal *, integer *, integer *);
      static integer lwkopt;
      static logical lquery;
  #define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
  
  
      a_dim1 = *lda;
      a_offset = 1 + a_dim1 * 1;
      a -= a_offset;
      --tau;
      --work;
  
      /* Function Body */
      *info = 0;
      lquery = *lwork == -1;
      upper = lsame_(uplo, "U");
      if (! upper && ! lsame_(uplo, "L")) {
  	*info = -1;
      } else if (*n < 0) {
  	*info = -2;
      } else if (*lda < max(1,*n)) {
  	*info = -4;
      } else /* if(complicated condition) */ {
  /* Computing MAX */
  	i__1 = 1, i__2 = *n - 1;
  	if (*lwork < max(i__1,i__2) && ! lquery) {
  	    *info = -7;
  	}
      }
  
      if (*info == 0) {
  	if (upper) {
  	    i__1 = *n - 1;
  	    i__2 = *n - 1;
  	    i__3 = *n - 1;
  	    nb = ilaenv_(&c__1, "DORGQL", " ", &i__1, &i__2, &i__3, &c_n1, (
  		    ftnlen)6, (ftnlen)1);
  	} else {
  	    i__1 = *n - 1;
  	    i__2 = *n - 1;
  	    i__3 = *n - 1;
  	    nb = ilaenv_(&c__1, "DORGQR", " ", &i__1, &i__2, &i__3, &c_n1, (
  		    ftnlen)6, (ftnlen)1);
  	}
  /* Computing MAX */
  	i__1 = 1, i__2 = *n - 1;
  	lwkopt = max(i__1,i__2) * nb;
  	work[1] = (doublereal) lwkopt;
      }
  
      if (*info != 0) {
  	i__1 = -(*info);
  	xerbla_("DORGTR", &i__1);
  	return 0;
      } else if (lquery) {
  	return 0;
      }
  
  /*     Quick return if possible */
  
      if (*n == 0) {
  	work[1] = 1.;
  	return 0;
      }
  
      if (upper) {
  
  /*        Q was determined by a call to DSYTRD with UPLO = 'U'   
  
            Shift the vectors which define the elementary reflectors one   
            column to the left, and set the last row and column of Q to   
            those of the unit matrix */
  
  	i__1 = *n - 1;
  	for (j = 1; j <= i__1; ++j) {
  	    i__2 = j - 1;
  	    for (i__ = 1; i__ <= i__2; ++i__) {
  		a_ref(i__, j) = a_ref(i__, j + 1);
  /* L10: */
  	    }
  	    a_ref(*n, j) = 0.;
  /* L20: */
  	}
  	i__1 = *n - 1;
  	for (i__ = 1; i__ <= i__1; ++i__) {
  	    a_ref(i__, *n) = 0.;
  /* L30: */
  	}
  	a_ref(*n, *n) = 1.;
  
  /*        Generate Q(1:n-1,1:n-1) */
  
  	i__1 = *n - 1;
  	i__2 = *n - 1;
  	i__3 = *n - 1;
  	dorgql_(&i__1, &i__2, &i__3, &a[a_offset], lda, &tau[1], &work[1], 
  		lwork, &iinfo);
  
      } else {
  
  /*        Q was determined by a call to DSYTRD with UPLO = 'L'.   
  
            Shift the vectors which define the elementary reflectors one   
            column to the right, and set the first row and column of Q to   
            those of the unit matrix */
  
  	for (j = *n; j >= 2; --j) {
  	    a_ref(1, j) = 0.;
  	    i__1 = *n;
  	    for (i__ = j + 1; i__ <= i__1; ++i__) {
  		a_ref(i__, j) = a_ref(i__, j - 1);
  /* L40: */
  	    }
  /* L50: */
  	}
  	a_ref(1, 1) = 1.;
  	i__1 = *n;
  	for (i__ = 2; i__ <= i__1; ++i__) {
  	    a_ref(i__, 1) = 0.;
  /* L60: */
  	}
  	if (*n > 1) {
  
  /*           Generate Q(2:n,2:n) */
  
  	    i__1 = *n - 1;
  	    i__2 = *n - 1;
  	    i__3 = *n - 1;
  	    dorgqr_(&i__1, &i__2, &i__3, &a_ref(2, 2), lda, &tau[1], &work[1],
  		     lwork, &iinfo);
  	}
      }
      work[1] = (doublereal) lwkopt;
      return 0;
  
  /*     End of DORGTR */
  
  } /* dorgtr_ */
  
  #undef a_ref
  
  #ifdef __cplusplus
  }
  #endif
  