OpenBLAS/lapack-netlib/SRC/sgehrd.c

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <complex.h>
#ifdef complex
#undef complex
#endif
#ifdef I
#undef I
#endif

#if defined(_WIN64)
typedef long long BLASLONG;
typedef unsigned long long BLASULONG;
#else
typedef long BLASLONG;
typedef unsigned long BLASULONG;
#endif

#ifdef LAPACK_ILP64
typedef BLASLONG blasint;
#if defined(_WIN64)
#define blasabs(x) llabs(x)
#else
#define blasabs(x) labs(x)
#endif
#else
typedef int blasint;
#define blasabs(x) abs(x)
#endif

typedef blasint integer;

typedef unsigned int uinteger;
typedef char *address;
typedef short int shortint;
typedef float real;
typedef double doublereal;
typedef struct { real r, i; } complex;
typedef struct { doublereal r, i; } doublecomplex;
#ifdef _MSC_VER
static inline _Fcomplex Cf(complex *z) {_Fcomplex zz={z->r , z->i}; return zz;}
static inline _Dcomplex Cd(doublecomplex *z) {_Dcomplex zz={z->r , z->i};return zz;}
static inline _Fcomplex * _pCf(complex *z) {return (_Fcomplex*)z;}
static inline _Dcomplex * _pCd(doublecomplex *z) {return (_Dcomplex*)z;}
#else
static inline _Complex float Cf(complex *z) {return z->r + z->i*_Complex_I;}
static inline _Complex double Cd(doublecomplex *z) {return z->r + z->i*_Complex_I;}
static inline _Complex float * _pCf(complex *z) {return (_Complex float*)z;}
static inline _Complex double * _pCd(doublecomplex *z) {return (_Complex double*)z;}
#endif
#define pCf(z) (*_pCf(z))
#define pCd(z) (*_pCd(z))
typedef blasint logical;

typedef char logical1;
typedef char integer1;

#define TRUE_ (1)
#define FALSE_ (0)

/* Extern is for use with -E */
#ifndef Extern
#define Extern extern
#endif

/* I/O stuff */

typedef int flag;
typedef int ftnlen;
typedef int ftnint;

/*external read, write*/
typedef struct
{	flag cierr;
	ftnint ciunit;
	flag ciend;
	char *cifmt;
	ftnint cirec;
} cilist;

/*internal read, write*/
typedef struct
{	flag icierr;
	char *iciunit;
	flag iciend;
	char *icifmt;
	ftnint icirlen;
	ftnint icirnum;
} icilist;

/*open*/
typedef struct
{	flag oerr;
	ftnint ounit;
	char *ofnm;
	ftnlen ofnmlen;
	char *osta;
	char *oacc;
	char *ofm;
	ftnint orl;
	char *oblnk;
} olist;

/*close*/
typedef struct
{	flag cerr;
	ftnint cunit;
	char *csta;
} cllist;

/*rewind, backspace, endfile*/
typedef struct
{	flag aerr;
	ftnint aunit;
} alist;

/* inquire */
typedef struct
{	flag inerr;
	ftnint inunit;
	char *infile;
	ftnlen infilen;
	ftnint	*inex;	/*parameters in standard's order*/
	ftnint	*inopen;
	ftnint	*innum;
	ftnint	*innamed;
	char	*inname;
	ftnlen	innamlen;
	char	*inacc;
	ftnlen	inacclen;
	char	*inseq;
	ftnlen	inseqlen;
	char 	*indir;
	ftnlen	indirlen;
	char	*infmt;
	ftnlen	infmtlen;
	char	*inform;
	ftnint	informlen;
	char	*inunf;
	ftnlen	inunflen;
	ftnint	*inrecl;
	ftnint	*innrec;
	char	*inblank;
	ftnlen	inblanklen;
} inlist;

#define VOID void

union Multitype {	/* for multiple entry points */
	integer1 g;
	shortint h;
	integer i;
	/* longint j; */
	real r;
	doublereal d;
	complex c;
	doublecomplex z;
	};

typedef union Multitype Multitype;

struct Vardesc {	/* for Namelist */
	char *name;
	char *addr;
	ftnlen *dims;
	int  type;
	};
typedef struct Vardesc Vardesc;

struct Namelist {
	char *name;
	Vardesc **vars;
	int nvars;
	};
typedef struct Namelist Namelist;

#define abs(x) ((x) >= 0 ? (x) : -(x))
#define dabs(x) (fabs(x))
#define f2cmin(a,b) ((a) <= (b) ? (a) : (b))
#define f2cmax(a,b) ((a) >= (b) ? (a) : (b))
#define dmin(a,b) (f2cmin(a,b))
#define dmax(a,b) (f2cmax(a,b))
#define bit_test(a,b)	((a) >> (b) & 1)
#define bit_clear(a,b)	((a) & ~((uinteger)1 << (b)))
#define bit_set(a,b)	((a) |  ((uinteger)1 << (b)))

#define abort_() { sig_die("Fortran abort routine called", 1); }
#define c_abs(z) (cabsf(Cf(z)))
#define c_cos(R,Z) { pCf(R)=ccos(Cf(Z)); }
#ifdef _MSC_VER
#define c_div(c, a, b) {Cf(c)._Val[0] = (Cf(a)._Val[0]/Cf(b)._Val[0]); Cf(c)._Val[1]=(Cf(a)._Val[1]/Cf(b)._Val[1]);}
#define z_div(c, a, b) {Cd(c)._Val[0] = (Cd(a)._Val[0]/Cd(b)._Val[0]); Cd(c)._Val[1]=(Cd(a)._Val[1]/df(b)._Val[1]);}
#else
#define c_div(c, a, b) {pCf(c) = Cf(a)/Cf(b);}
#define z_div(c, a, b) {pCd(c) = Cd(a)/Cd(b);}
#endif
#define c_exp(R, Z) {pCf(R) = cexpf(Cf(Z));}
#define c_log(R, Z) {pCf(R) = clogf(Cf(Z));}
#define c_sin(R, Z) {pCf(R) = csinf(Cf(Z));}
//#define c_sqrt(R, Z) {*(R) = csqrtf(Cf(Z));}
#define c_sqrt(R, Z) {pCf(R) = csqrtf(Cf(Z));}
#define d_abs(x) (fabs(*(x)))
#define d_acos(x) (acos(*(x)))
#define d_asin(x) (asin(*(x)))
#define d_atan(x) (atan(*(x)))
#define d_atn2(x, y) (atan2(*(x),*(y)))
#define d_cnjg(R, Z) { pCd(R) = conj(Cd(Z)); }
#define r_cnjg(R, Z) { pCf(R) = conjf(Cf(Z)); }
#define d_cos(x) (cos(*(x)))
#define d_cosh(x) (cosh(*(x)))
#define d_dim(__a, __b) ( *(__a) > *(__b) ? *(__a) - *(__b) : 0.0 )
#define d_exp(x) (exp(*(x)))
#define d_imag(z) (cimag(Cd(z)))
#define r_imag(z) (cimagf(Cf(z)))
#define d_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
#define r_int(__x) (*(__x)>0 ? floor(*(__x)) : -floor(- *(__x)))
#define d_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
#define r_lg10(x) ( 0.43429448190325182765 * log(*(x)) )
#define d_log(x) (log(*(x)))
#define d_mod(x, y) (fmod(*(x), *(y)))
#define u_nint(__x) ((__x)>=0 ? floor((__x) + .5) : -floor(.5 - (__x)))
#define d_nint(x) u_nint(*(x))
#define u_sign(__a,__b) ((__b) >= 0 ? ((__a) >= 0 ? (__a) : -(__a)) : -((__a) >= 0 ? (__a) : -(__a)))
#define d_sign(a,b) u_sign(*(a),*(b))
#define r_sign(a,b) u_sign(*(a),*(b))
#define d_sin(x) (sin(*(x)))
#define d_sinh(x) (sinh(*(x)))
#define d_sqrt(x) (sqrt(*(x)))
#define d_tan(x) (tan(*(x)))
#define d_tanh(x) (tanh(*(x)))
#define i_abs(x) abs(*(x))
#define i_dnnt(x) ((integer)u_nint(*(x)))
#define i_len(s, n) (n)
#define i_nint(x) ((integer)u_nint(*(x)))
#define i_sign(a,b) ((integer)u_sign((integer)*(a),(integer)*(b)))
#define s_cat(lpp, rpp, rnp, np, llp) { 	ftnlen i, nc, ll; char *f__rp, *lp; 	ll = (llp); lp = (lpp); 	for(i=0; i < (int)*(np); ++i) {         	nc = ll; 	        if((rnp)[i] < nc) nc = (rnp)[i]; 	        ll -= nc;         	f__rp = (rpp)[i]; 	        while(--nc >= 0) *lp++ = *(f__rp)++;         } 	while(--ll >= 0) *lp++ = ' '; }
#define s_cmp(a,b,c,d) ((integer)strncmp((a),(b),f2cmin((c),(d))))
#define s_copy(A,B,C,D) { int __i,__m; for (__i=0, __m=f2cmin((C),(D)); __i<__m && (B)[__i] != 0; ++__i) (A)[__i] = (B)[__i]; }
#define sig_die(s, kill) { exit(1); }
#define s_stop(s, n) {exit(0);}
#define z_abs(z) (cabs(Cd(z)))
#define z_exp(R, Z) {pCd(R) = cexp(Cd(Z));}
#define z_sqrt(R, Z) {pCd(R) = csqrt(Cd(Z));}
#define myexit_() break;
#define mycycle() continue;
#define myceiling(w) {ceil(w)}
#define myhuge(w) {HUGE_VAL}
//#define mymaxloc_(w,s,e,n) {if (sizeof(*(w)) == sizeof(double)) dmaxloc_((w),*(s),*(e),n); else dmaxloc_((w),*(s),*(e),n);}
#define mymaxloc(w,s,e,n) {dmaxloc_(w,*(s),*(e),n)}

/*  -- translated by f2c (version 20000121).
   You must link the resulting object file with the libraries:
	-lf2c -lm   (in that order)
*/




/* Table of constant values */

static integer c__1 = 1;
static integer c_n1 = -1;
static integer c__3 = 3;
static integer c__2 = 2;
static integer c__65 = 65;
static real c_b25 = -1.f;
static real c_b26 = 1.f;

/* > \brief \b SGEHRD */

/*  =========== DOCUMENTATION =========== */

/* Online html documentation available at */
/*            http://www.netlib.org/lapack/explore-html/ */

/* > \htmlonly */
/* > Download SGEHRD + dependencies */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sgehrd.
f"> */
/* > [TGZ]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sgehrd.
f"> */
/* > [ZIP]</a> */
/* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sgehrd.
f"> */
/* > [TXT]</a> */
/* > \endhtmlonly */

/*  Definition: */
/*  =========== */

/*       SUBROUTINE SGEHRD( N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO ) */

/*       INTEGER            IHI, ILO, INFO, LDA, LWORK, N */
/*       REAL              A( LDA, * ), TAU( * ), WORK( * ) */


/* > \par Purpose: */
/*  ============= */
/* > */
/* > \verbatim */
/* > */
/* > SGEHRD reduces a real general matrix A to upper Hessenberg form H by */
/* > an orthogonal similarity transformation:  Q**T * A * Q = H . */
/* > \endverbatim */

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

/* > \param[in] N */
/* > \verbatim */
/* >          N is INTEGER */
/* >          The order of the matrix A.  N >= 0. */
/* > \endverbatim */
/* > */
/* > \param[in] ILO */
/* > \verbatim */
/* >          ILO is INTEGER */
/* > \endverbatim */
/* > */
/* > \param[in] IHI */
/* > \verbatim */
/* >          IHI is INTEGER */
/* > */
/* >          It is assumed that A is already upper triangular in rows */
/* >          and columns 1:ILO-1 and IHI+1:N. ILO and IHI are normally */
/* >          set by a previous call to SGEBAL; otherwise they should be */
/* >          set to 1 and N respectively. See Further Details. */
/* >          1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0. */
/* > \endverbatim */
/* > */
/* > \param[in,out] A */
/* > \verbatim */
/* >          A is REAL array, dimension (LDA,N) */
/* >          On entry, the N-by-N general matrix to be reduced. */
/* >          On exit, the upper triangle and the first subdiagonal of A */
/* >          are overwritten with the upper Hessenberg matrix H, and the */
/* >          elements below the first subdiagonal, with the array TAU, */
/* >          represent the orthogonal matrix Q as a product of elementary */
/* >          reflectors. See Further Details. */
/* > \endverbatim */
/* > */
/* > \param[in] LDA */
/* > \verbatim */
/* >          LDA is INTEGER */
/* >          The leading dimension of the array A.  LDA >= f2cmax(1,N). */
/* > \endverbatim */
/* > */
/* > \param[out] TAU */
/* > \verbatim */
/* >          TAU is REAL array, dimension (N-1) */
/* >          The scalar factors of the elementary reflectors (see Further */
/* >          Details). Elements 1:ILO-1 and IHI:N-1 of TAU are set to */
/* >          zero. */
/* > \endverbatim */
/* > */
/* > \param[out] WORK */
/* > \verbatim */
/* >          WORK is REAL array, dimension (LWORK) */
/* >          On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
/* > \endverbatim */
/* > */
/* > \param[in] LWORK */
/* > \verbatim */
/* >          LWORK is INTEGER */
/* >          The length of the array WORK.  LWORK >= f2cmax(1,N). */
/* >          For good performance, LWORK should generally be larger. */
/* > */
/* >          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. */
/* > \endverbatim */
/* > */
/* > \param[out] INFO */
/* > \verbatim */
/* >          INFO is INTEGER */
/* >          = 0:  successful exit */
/* >          < 0:  if INFO = -i, the i-th argument had an illegal value. */
/* > \endverbatim */

/*  Authors: */
/*  ======== */

/* > \author Univ. of Tennessee */
/* > \author Univ. of California Berkeley */
/* > \author Univ. of Colorado Denver */
/* > \author NAG Ltd. */

/* > \date December 2016 */

/* > \ingroup realGEcomputational */

/* > \par Further Details: */
/*  ===================== */
/* > */
/* > \verbatim */
/* > */
/* >  The matrix Q is represented as a product of (ihi-ilo) elementary */
/* >  reflectors */
/* > */
/* >     Q = H(ilo) H(ilo+1) . . . H(ihi-1). */
/* > */
/* >  Each H(i) has the form */
/* > */
/* >     H(i) = I - tau * v * v**T */
/* > */
/* >  where tau is a real scalar, and v is a real vector with */
/* >  v(1:i) = 0, v(i+1) = 1 and v(ihi+1:n) = 0; v(i+2:ihi) is stored on */
/* >  exit in A(i+2:ihi,i), and tau in TAU(i). */
/* > */
/* >  The contents of A are illustrated by the following example, with */
/* >  n = 7, ilo = 2 and ihi = 6: */
/* > */
/* >  on entry,                        on exit, */
/* > */
/* >  ( a   a   a   a   a   a   a )    (  a   a   h   h   h   h   a ) */
/* >  (     a   a   a   a   a   a )    (      a   h   h   h   h   a ) */
/* >  (     a   a   a   a   a   a )    (      h   h   h   h   h   h ) */
/* >  (     a   a   a   a   a   a )    (      v2  h   h   h   h   h ) */
/* >  (     a   a   a   a   a   a )    (      v2  v3  h   h   h   h ) */
/* >  (     a   a   a   a   a   a )    (      v2  v3  v4  h   h   h ) */
/* >  (                         a )    (                          a ) */
/* > */
/* >  where a denotes an element of the original matrix A, h denotes a */
/* >  modified element of the upper Hessenberg matrix H, and vi denotes an */
/* >  element of the vector defining H(i). */
/* > */
/* >  This file is a slight modification of LAPACK-3.0's DGEHRD */
/* >  subroutine incorporating improvements proposed by Quintana-Orti and */
/* >  Van de Geijn (2006). (See DLAHR2.) */
/* > \endverbatim */
/* > */
/*  ===================================================================== */
/* Subroutine */ void sgehrd_(integer *n, integer *ilo, integer *ihi, real *a, 
	integer *lda, real *tau, real *work, integer *lwork, integer *info)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3, i__4;

    /* Local variables */
    integer i__, j, nbmin, iinfo;
    extern /* Subroutine */ void sgemm_(char *, char *, integer *, integer *, 
	    integer *, real *, real *, integer *, real *, integer *, real *, 
	    real *, integer *), strmm_(char *, char *, char *,
	     char *, integer *, integer *, real *, real *, integer *, real *, 
	    integer *), saxpy_(integer *, 
	    real *, real *, integer *, real *, integer *), sgehd2_(integer *, 
	    integer *, integer *, real *, integer *, real *, real *, integer *
	    ), slahr2_(integer *, integer *, integer *, real *, integer *, 
	    real *, real *, integer *, real *, integer *);
    integer ib;
    real ei;
    integer nb, nh, nx;
    extern /* Subroutine */ void slarfb_(char *, char *, char *, char *, 
	    integer *, integer *, integer *, real *, integer *, real *, 
	    integer *, real *, integer *, real *, integer *);
    extern int xerbla_(char *, integer *,ftnlen);
    extern integer ilaenv_(integer *, char *, char *, integer *, integer *, 
	    integer *, integer *, ftnlen, ftnlen);
    integer ldwork, lwkopt;
    logical lquery;
    integer iwt;


/*  -- LAPACK computational routine (version 3.7.0) -- */
/*  -- LAPACK is a software package provided by Univ. of Tennessee,    -- */
/*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
/*     December 2016 */


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


/*     Test the input parameters */

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

    /* Function Body */
    *info = 0;
    lquery = *lwork == -1;
    if (*n < 0) {
	*info = -1;
    } else if (*ilo < 1 || *ilo > f2cmax(1,*n)) {
	*info = -2;
    } else if (*ihi < f2cmin(*ilo,*n) || *ihi > *n) {
	*info = -3;
    } else if (*lda < f2cmax(1,*n)) {
	*info = -5;
    } else if (*lwork < f2cmax(1,*n) && ! lquery) {
	*info = -8;
    }

    if (*info == 0) {

/*       Compute the workspace requirements */

/* Computing MIN */
	i__1 = 64, i__2 = ilaenv_(&c__1, "SGEHRD", " ", n, ilo, ihi, &c_n1, (
		ftnlen)6, (ftnlen)1);
	nb = f2cmin(i__1,i__2);
	lwkopt = *n * nb + 4160;
	work[1] = (real) lwkopt;
    }

    if (*info != 0) {
	i__1 = -(*info);
	xerbla_("SGEHRD", &i__1, (ftnlen)6);
	return;
    } else if (lquery) {
	return;
    }

/*     Set elements 1:ILO-1 and IHI:N-1 of TAU to zero */

    i__1 = *ilo - 1;
    for (i__ = 1; i__ <= i__1; ++i__) {
	tau[i__] = 0.f;
/* L10: */
    }
    i__1 = *n - 1;
    for (i__ = f2cmax(1,*ihi); i__ <= i__1; ++i__) {
	tau[i__] = 0.f;
/* L20: */
    }

/*     Quick return if possible */

    nh = *ihi - *ilo + 1;
    if (nh <= 1) {
	work[1] = 1.f;
	return;
    }

/*     Determine the block size */

/* Computing MIN */
    i__1 = 64, i__2 = ilaenv_(&c__1, "SGEHRD", " ", n, ilo, ihi, &c_n1, (
	    ftnlen)6, (ftnlen)1);
    nb = f2cmin(i__1,i__2);
    nbmin = 2;
    if (nb > 1 && nb < nh) {

/*        Determine when to cross over from blocked to unblocked code */
/*        (last block is always handled by unblocked code) */

/* Computing MAX */
	i__1 = nb, i__2 = ilaenv_(&c__3, "SGEHRD", " ", n, ilo, ihi, &c_n1, (
		ftnlen)6, (ftnlen)1);
	nx = f2cmax(i__1,i__2);
	if (nx < nh) {

/*           Determine if workspace is large enough for blocked code */

	    if (*lwork < *n * nb + 4160) {

/*              Not enough workspace to use optimal NB:  determine the */
/*              minimum value of NB, and reduce NB or force use of */
/*              unblocked code */

/* Computing MAX */
		i__1 = 2, i__2 = ilaenv_(&c__2, "SGEHRD", " ", n, ilo, ihi, &
			c_n1, (ftnlen)6, (ftnlen)1);
		nbmin = f2cmax(i__1,i__2);
		if (*lwork >= *n * nbmin + 4160) {
		    nb = (*lwork - 4160) / *n;
		} else {
		    nb = 1;
		}
	    }
	}
    }
    ldwork = *n;

    if (nb < nbmin || nb >= nh) {

/*        Use unblocked code below */

	i__ = *ilo;

    } else {

/*        Use blocked code */

	iwt = *n * nb + 1;
	i__1 = *ihi - 1 - nx;
	i__2 = nb;
	for (i__ = *ilo; i__2 < 0 ? i__ >= i__1 : i__ <= i__1; i__ += i__2) {
/* Computing MIN */
	    i__3 = nb, i__4 = *ihi - i__;
	    ib = f2cmin(i__3,i__4);

/*           Reduce columns i:i+ib-1 to Hessenberg form, returning the */
/*           matrices V and T of the block reflector H = I - V*T*V**T */
/*           which performs the reduction, and also the matrix Y = A*V*T */

	    slahr2_(ihi, &i__, &ib, &a[i__ * a_dim1 + 1], lda, &tau[i__], &
		    work[iwt], &c__65, &work[1], &ldwork);

/*           Apply the block reflector H to A(1:ihi,i+ib:ihi) from the */
/*           right, computing  A := A - Y * V**T. V(i+ib,ib-1) must be set */
/*           to 1 */

	    ei = a[i__ + ib + (i__ + ib - 1) * a_dim1];
	    a[i__ + ib + (i__ + ib - 1) * a_dim1] = 1.f;
	    i__3 = *ihi - i__ - ib + 1;
	    sgemm_("No transpose", "Transpose", ihi, &i__3, &ib, &c_b25, &
		    work[1], &ldwork, &a[i__ + ib + i__ * a_dim1], lda, &
		    c_b26, &a[(i__ + ib) * a_dim1 + 1], lda);
	    a[i__ + ib + (i__ + ib - 1) * a_dim1] = ei;

/*           Apply the block reflector H to A(1:i,i+1:i+ib-1) from the */
/*           right */

	    i__3 = ib - 1;
	    strmm_("Right", "Lower", "Transpose", "Unit", &i__, &i__3, &c_b26,
		     &a[i__ + 1 + i__ * a_dim1], lda, &work[1], &ldwork);
	    i__3 = ib - 2;
	    for (j = 0; j <= i__3; ++j) {
		saxpy_(&i__, &c_b25, &work[ldwork * j + 1], &c__1, &a[(i__ + 
			j + 1) * a_dim1 + 1], &c__1);
/* L30: */
	    }

/*           Apply the block reflector H to A(i+1:ihi,i+ib:n) from the */
/*           left */

	    i__3 = *ihi - i__;
	    i__4 = *n - i__ - ib + 1;
	    slarfb_("Left", "Transpose", "Forward", "Columnwise", &i__3, &
		    i__4, &ib, &a[i__ + 1 + i__ * a_dim1], lda, &work[iwt], &
		    c__65, &a[i__ + 1 + (i__ + ib) * a_dim1], lda, &work[1], &
		    ldwork);
/* L40: */
	}
    }

/*     Use unblocked code to reduce the rest of the matrix */

    sgehd2_(n, &i__, ihi, &a[a_offset], lda, &tau[1], &work[1], &iinfo);
    work[1] = (real) lwkopt;

    return;

/*     End of SGEHRD */

} /* sgehrd_ */