コード例 #1
0
ファイル: ssygvd.cpp プロジェクト: cjy7117/DVFS-MAGMA
extern "C" magma_int_t
magma_ssygvd(magma_int_t itype, char jobz, char uplo, magma_int_t n,
             float *a, magma_int_t lda, float *b, magma_int_t ldb, 
             float *w, float *work, magma_int_t lwork, 
             magma_int_t *iwork, magma_int_t liwork, magma_int_t *info)
{
/*  -- MAGMA (version 1.3.0) --
       Univ. of Tennessee, Knoxville
       Univ. of California, Berkeley
       Univ. of Colorado, Denver
       November 2012

    Purpose   
    =======   
    SSYGVD computes all the eigenvalues, and optionally, the eigenvectors   
    of a real generalized symmetric-definite eigenproblem, of the form   
    A*x=(lambda)*B*x,  A*Bx=(lambda)*x,  or B*A*x=(lambda)*x.  Here A and   
    B are assumed to be symmetric and B is also positive definite.   
    If eigenvectors are desired, it uses a divide and conquer algorithm.   

    The divide and conquer algorithm makes very mild assumptions about   
    floating point arithmetic. It will work on machines with a guard   
    digit in add/subtract, or on those binary machines without guard   
    digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or   
    Cray-2. It could conceivably fail on hexadecimal or decimal machines   
    without guard digits, but we know of none.   

    Arguments   
    =========   
    ITYPE   (input) INTEGER   
            Specifies the problem type to be solved:   
            = 1:  A*x = (lambda)*B*x   
            = 2:  A*B*x = (lambda)*x   
            = 3:  B*A*x = (lambda)*x   

    JOBZ    (input) CHARACTER*1   
            = 'N':  Compute eigenvalues only;   
            = 'V':  Compute eigenvalues and eigenvectors.   

    UPLO    (input) CHARACTER*1   
            = 'U':  Upper triangles of A and B are stored;   
            = 'L':  Lower triangles of A and B are stored.   

    N       (input) INTEGER   
            The order of the matrices A and B.  N >= 0.   

    A       (input/output) COMPLEX*16 array, dimension (LDA, N)   
            On entry, the symmetric matrix A.  If UPLO = 'U', the   
            leading N-by-N upper triangular part of A contains the   
            upper triangular part of the matrix A.  If UPLO = 'L',   
            the leading N-by-N lower triangular part of A contains   
            the lower triangular part of the matrix A.   

            On exit, if JOBZ = 'V', then if INFO = 0, A contains the   
            matrix Z of eigenvectors.  The eigenvectors are normalized   
            as follows:   
            if ITYPE = 1 or 2, Z**T *   B    * Z = I;   
            if ITYPE = 3,      Z**T * inv(B) * Z = I.   
            If JOBZ = 'N', then on exit the upper triangle (if UPLO='U')   
            or the lower triangle (if UPLO='L') of A, including the   
            diagonal, is destroyed.   

    LDA     (input) INTEGER   
            The leading dimension of the array A.  LDA >= max(1,N).   

    B       (input/output) COMPLEX*16 array, dimension (LDB, N)   
            On entry, the symmetric matrix B.  If UPLO = 'U', the   
            leading N-by-N upper triangular part of B contains the   
            upper triangular part of the matrix B.  If UPLO = 'L',   
            the leading N-by-N lower triangular part of B contains   
            the lower triangular part of the matrix B.   

            On exit, if INFO <= N, the part of B containing the matrix is   
            overwritten by the triangular factor U or L from the Cholesky   
            factorization B = U**T * U or B = L * L**T.   

    LDB     (input) INTEGER   
            The leading dimension of the array B.  LDB >= max(1,N).   

    W       (output) DOUBLE PRECISION array, dimension (N)   
            If INFO = 0, the eigenvalues in ascending order.   

    WORK    (workspace/output) COMPLEX*16 array, dimension (MAX(1,LWORK))   
            On exit, if INFO = 0, WORK(1) returns the optimal LWORK.   

    LWORK   (input) INTEGER   
            The length of the array WORK.   
            If N <= 1,                LWORK >= 1.   
            If JOBZ  = 'N' and N > 1, LWORK >= 2*N*nb + 1.   
            If JOBZ  = 'V' and N > 1, LWORK >= 1 + 6*N*nb + 2*N**2.   

            If LWORK = -1, then a workspace query is assumed; the routine   
            only calculates the optimal sizes of the WORK and   
            IWORK arrays, returns these values as the first entries of   
            the WORK and IWORK arrays, and no error message   
            related to LWORK or LIWORK is issued by XERBLA.   

    IWORK   (workspace/output) INTEGER array, dimension (MAX(1,LIWORK))   
            On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.   

    LIWORK  (input) INTEGER   
            The dimension of the array IWORK.   
            If N <= 1,                LIWORK >= 1.   
            If JOBZ  = 'N' and N > 1, LIWORK >= 1.   
            If JOBZ  = 'V' and N > 1, LIWORK >= 3 + 5*N.   

            If LIWORK = -1, then a workspace query is assumed; the   
            routine only calculates the optimal sizes of the WORK   
            and IWORK arrays, returns these values as the first entries   
            of the WORK and IWORK arrays, and no error message   
            related to LWORK or LIWORK is issued by XERBLA.   

    INFO    (output) INTEGER   
            = 0:  successful exit   
            < 0:  if INFO = -i, the i-th argument had an illegal value   
            > 0:  SPOTRF or SSYEVD returned an error code:   
               <= N:  if INFO = i and JOBZ = 'N', then the algorithm   
                      failed to converge; i off-diagonal elements of an   
                      intermediate tridiagonal form did not converge to   
                      zero;   
                      if INFO = i and JOBZ = 'V', then the algorithm   
                      failed to compute an eigenvalue while working on   
                      the submatrix lying in rows and columns INFO/(N+1)   
                      through mod(INFO,N+1);   
               > N:   if INFO = N + i, for 1 <= i <= N, then the leading   
                      minor of order i of B is not positive definite.   
                      The factorization of B could not be completed and   
                      no eigenvalues or eigenvectors were computed.   

    Further Details   
    ===============   

    Based on contributions by   
       Mark Fahey, Department of Mathematics, Univ. of Kentucky, USA   

    Modified so that no backsubstitution is performed if SSYEVD fails to   
    converge (NEIG in old code could be greater than N causing out of   
    bounds reference to A - reported by Ralf Meyer).  Also corrected the   
    description of INFO and the test on ITYPE. Sven, 16 Feb 05.   
    =====================================================================  */

    char uplo_[2] = {uplo, 0};
    char jobz_[2] = {jobz, 0};

    float d_one = MAGMA_S_ONE;
    
    float *da;
    float *db;
    magma_int_t ldda = n;
    magma_int_t lddb = n;

    magma_int_t lower;
    char trans[1];
    magma_int_t wantz, lquery;

    magma_int_t lopt, lwmin, liopt, liwmin;
  
    cudaStream_t stream;
    magma_queue_create( &stream );

    wantz = lapackf77_lsame(jobz_, MagmaVectorsStr);
    lower = lapackf77_lsame(uplo_, MagmaLowerStr);
    lquery = lwork == -1 || liwork == -1;

    *info = 0;
    if (itype < 1 || itype > 3) {
        *info = -1;
    } else if (! (wantz || lapackf77_lsame(jobz_, MagmaNoVectorsStr))) {
        *info = -2;
    } else if (! (lower || lapackf77_lsame(uplo_, MagmaUpperStr))) {
        *info = -3;
    } else if (n < 0) {
        *info = -4;
    } else if (lda < max(1,n)) {
        *info = -6;
    } else if (ldb < max(1,n)) {
        *info = -8;
    }

    magma_int_t nb = magma_get_ssytrd_nb(n); 
  
    if (n < 1) {
      liwmin = 1;
      lwmin = 1;
    } else if (wantz) {
      lwmin = 1 + 6 * n * nb + 2* n * n;
      liwmin = 5 * n + 3;
    } else {
        lwmin = 2 * n * nb + 1;
        liwmin = 1;
    }

    lopt = lwmin;
    liopt = liwmin;

    work[ 0] =  lopt;
    iwork[0] = liopt;

    if (lwork < lwmin && ! lquery) {
        *info = -11;
    } else if (liwork < liwmin && ! lquery) {
         *info = -13;
    }

    if (*info != 0) {
        magma_xerbla( __func__, -(*info) );
        return MAGMA_ERR_ILLEGAL_VALUE;
    }
    else if (lquery) {
        return MAGMA_SUCCESS;
    }

    /*  Quick return if possible */
    if (n == 0) {
        return 0;
    }

    if (MAGMA_SUCCESS != magma_smalloc( &da, n*ldda ) ||
        MAGMA_SUCCESS != magma_smalloc( &db, n*lddb )) {
      *info = -17;
      return MAGMA_ERR_DEVICE_ALLOC;
    }
  
    /* Form a Cholesky factorization of B. */
    magma_ssetmatrix( n, n, b, ldb, db, lddb );

    magma_ssetmatrix_async( n, n,
                            a,  lda,
                            da, ldda, stream );  
  
    magma_spotrf_gpu(uplo_[0], n, db, lddb, info);
    if (*info != 0) {
        *info = n + *info;
        return 0;
    }

    magma_queue_sync( stream );
  
    magma_sgetmatrix_async( n, n,
                            db, lddb,
                            b,  ldb, stream );

    /*  Transform problem to standard eigenvalue problem and solve. */
    magma_ssygst_gpu(itype, uplo_[0], n, da, ldda, db, lddb, info);
  
    magma_ssyevd_gpu(jobz_[0], uplo_[0], n, da, ldda, w, a, lda, 
                     work, lwork, iwork, liwork, info);

    lopt  = max( lopt, (magma_int_t) work[0]);
    liopt = max(liopt, iwork[0]);

    if (wantz && *info == 0) 
      {
        /* Backtransform eigenvectors to the original problem. */
        if (itype == 1 || itype == 2) 
          {
            /* For A*x=(lambda)*B*x and A*B*x=(lambda)*x;   
               backtransform eigenvectors: x = inv(L)'*y or inv(U)*y */
            if (lower) {
                *(unsigned char *)trans = MagmaTrans;
            } else {
                *(unsigned char *)trans = MagmaNoTrans;
            }

            magma_strsm(MagmaLeft, uplo_[0], *trans, MagmaNonUnit,
                        n, n, d_one, db, lddb, da, ldda);

        } else if (itype == 3) 
          {
            /*  For B*A*x=(lambda)*x;   
                backtransform eigenvectors: x = L*y or U'*y */
            if (lower) {
                *(unsigned char *)trans = MagmaNoTrans;
            } else {
                *(unsigned char *)trans = MagmaTrans;
            }

            magma_strmm(MagmaLeft, uplo_[0], *trans, MagmaNonUnit, 
                        n, n, d_one, db, lddb, da, ldda);
        }

        magma_sgetmatrix( n, n, da, ldda, a, lda );

    }

    magma_queue_sync( stream );
    magma_queue_destroy( stream );
  
    work[0] = (float) lopt;
    iwork[0] = liopt;

    magma_free( da );
    magma_free( db );
  
    return MAGMA_SUCCESS;
} /* magma_ssygvd */
コード例 #2
0
ファイル: magma_eigh.c プロジェクト: DEVESHTARASIA/Theano
int APPLY_SPECIFIC(magma_eigh)(PyGpuArrayObject *A_,
                               PyGpuArrayObject **D,
                               PyGpuArrayObject **V, // may be NULL
                               PARAMS_TYPE *params) {
  PyGpuArrayObject *A = NULL;
  magma_int_t N, liwork, *iwork_data = NULL;
  size_t d_dims[1], v_dims[2];
  magma_uplo_t uplo;
  magma_vec_t jobz;
  float *w_data = NULL, *wA_data = NULL, *work_data = NULL, lwork;
  int res = -1, info;

  if (A_->ga.typecode != GA_FLOAT) {
    PyErr_SetString(PyExc_TypeError,
                    "GpuMagmaEigh: Unsupported data type");
    return -1;
  }

  // This is early to match the exit() in the fail label.
  cuda_enter(params->context->ctx);

  if (!GpuArray_IS_C_CONTIGUOUS(&A_->ga)) {
    PyErr_SetString(PyExc_ValueError,
                    "GpuMagmaEigh: requires data to be C-contiguous");
    goto fail;
  }
  if (PyGpuArray_NDIM(A_) != 2) {
    PyErr_SetString(PyExc_ValueError,
                    "GpuMagmaEigh: matrix rank error");
    goto fail;
  }
  if (PyGpuArray_DIM(A_, 0) != PyGpuArray_DIM(A_, 1)) {
    PyErr_SetString(PyExc_ValueError,
                    "GpuMagmaEigh: matrix is not square");
    goto fail;
  }

  A = pygpu_copy(A_, GA_F_ORDER);
  if (A == NULL) {
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to change to column-major order");
    return -1;
  }

  // magma matrix eigen decomposition of a symmetric matrix
  N = PyGpuArray_DIM(A, 0);

  if (params->lower) {
    uplo = MagmaLower;
  } else {
    uplo = MagmaUpper;
  }
  if (params->compute_v) {
    jobz = MagmaVec;
  } else {
    jobz = MagmaNoVec;
  }

  if (MAGMA_SUCCESS != magma_smalloc_pinned(&w_data, N)) {
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to allocate working memory");
    goto fail;
  }
  if (MAGMA_SUCCESS != magma_smalloc_pinned(&wA_data, N * N)) {
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to allocate working memory");
    goto fail;
  }

  // query for workspace size
  magma_ssyevd_gpu(jobz, uplo, N, NULL, N, NULL, NULL, N, &lwork,
                   -1, &liwork, -1, &info);

  if (MAGMA_SUCCESS != magma_smalloc_pinned(&work_data, (size_t)lwork)) {
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to allocate working memory");
    goto fail;
  }
  if (MAGMA_SUCCESS != magma_imalloc_cpu(&iwork_data, liwork)) {
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to allocate working memory");
    goto fail;
  }

  magma_ssyevd_gpu(jobz, uplo, N, (float *)PyGpuArray_DEV_DATA(A), N, w_data,
                   wA_data, N, work_data, (size_t)lwork, iwork_data, liwork,
                   &info);
  if (info > 0) {
    PyErr_Format(
        PyExc_RuntimeError,
        "GpuMagmaEigh:  %d off-diagonal elements of an didn't converge to zero",
        info);
    goto fail;
  } else if (info < 0) {
    PyErr_Format(
        PyExc_RuntimeError,
        "GpuMagmaEigh: magma_ssyevd_gpu argument %d has an illegal value", -info);
    goto fail;
  }

  d_dims[0] = N;
  if (theano_prep_output(D, 1, d_dims, A->ga.typecode, GA_C_ORDER, params->context) != 0){
    PyErr_SetString(PyExc_RuntimeError,
                    "GpuMagmaEigh: failed to allocate memory for the output");
    goto fail;
  }
  cudaMemcpy(PyGpuArray_DEV_DATA(*D), w_data, N * sizeof(float),
             cudaMemcpyDeviceToDevice);

  if (params->compute_v) {
    *V = theano_try_copy(*V, A);
    if (*V == NULL) {
      PyErr_SetString(PyExc_RuntimeError,
                      "GpuMagmaEigh: failed to allocate memory for the output");
      goto fail;
    }
  }
  res = 0;
fail:
  if (w_data != NULL)
    magma_free_pinned(w_data);
  if (wA_data != NULL)
    magma_free_pinned(wA_data);
  if (work_data != NULL)
    magma_free_pinned(work_data);
  if (iwork_data != NULL)
    magma_free_cpu(iwork_data);
  Py_XDECREF(A);
  cuda_exit(params->context->ctx);
  return res;
}
コード例 #3
0
ファイル: slobpcg.cpp プロジェクト: EmergentOrder/magma
extern "C" magma_int_t
magma_slobpcg( magma_s_sparse_matrix A, magma_s_solver_par *solver_par ) {


#define  residualNorms(i,iter)  ( residualNorms + (i) + (iter)*n )
#define magmablas_swap(x, y)    { pointer = x; x = y; y = pointer; }
#define hresidualNorms(i,iter)  (hresidualNorms + (i) + (iter)*n )

#define gramA(    m, n)   (gramA     + (m) + (n)*ldgram)
#define gramB(    m, n)   (gramB     + (m) + (n)*ldgram)
#define gevectors(m, n)   (gevectors + (m) + (n)*ldgram)
#define h_gramB(  m, n)   (h_gramB   + (m) + (n)*ldgram)

#define magma_s_bspmv_tuned(m, n, alpha, A, X, beta, AX)       {        \
            magmablas_stranspose( m, n, X, m, blockW, n );        	\
            magma_s_vector x, ax;                                       \
            x.memory_location = Magma_DEV;  x.num_rows = m*n;  x.nnz = m*n;  x.val = blockW; \
            ax.memory_location= Magma_DEV; ax.num_rows = m*n; ax.nnz = m*n; ax.val = AX;     \
            magma_s_spmv(alpha, A, x, beta, ax );                           \
            magmablas_stranspose( n, m, blockW, n, X, m );            		\
}




//**************************************************************

    // Memory allocation for the eigenvectors, eigenvalues, and workspace
    solver_par->solver = Magma_LOBPCG;
    magma_int_t m = A.num_rows;
    magma_int_t n =(solver_par->num_eigenvalues);
    float *blockX = solver_par->eigenvectors;
    float *evalues = solver_par->eigenvalues;


    float *dwork, *hwork;
    float *blockP, *blockAP, *blockR, *blockAR, *blockAX, *blockW;
    float *gramA, *gramB, *gramM;
    float *gevectors, *h_gramB;

    float *pointer, *origX = blockX;
    float *eval_gpu;

    magma_int_t lwork = max( 2*n+n*magma_get_dsytrd_nb(n),
                             1 + 6*3*n + 2* 3*n* 3*n);

    magma_smalloc_pinned( &hwork   ,        lwork );
    magma_smalloc(        &blockAX   ,        m*n );
    magma_smalloc(        &blockAR   ,        m*n );
    magma_smalloc(        &blockAP   ,        m*n );
    magma_smalloc(        &blockR    ,        m*n );
    magma_smalloc(        &blockP    ,        m*n );
    magma_smalloc(        &blockW    ,        m*n );
    magma_smalloc(        &dwork     ,        m*n );
    magma_smalloc(        &eval_gpu  ,        3*n );




//**********************************************************+

    magma_int_t verbosity = 1;
    magma_int_t *iwork, liwork = 15*n+9;

    // === Set solver parameters ===
    float residualTolerance  = solver_par->epsilon;
    magma_int_t maxIterations = solver_par->maxiter;

    // === Set some constants & defaults ===
    float c_one = MAGMA_S_ONE, c_zero = MAGMA_S_ZERO;

    float *residualNorms, *condestGhistory, condestG;
    float *gevalues;
    magma_int_t *activeMask;

    // === Check some parameters for possible quick exit ===
    solver_par->info = 0;
    if (m < 2)
        solver_par->info = -1;
    else if (n > m)
        solver_par->info = -2;

    if (solver_par->info != 0) {
        magma_xerbla( __func__, -(solver_par->info) );
        return solver_par->info;
    }
    magma_int_t *info = &(solver_par->info); // local info variable;

    // === Allocate GPU memory for the residual norms' history ===
    magma_smalloc(&residualNorms, (maxIterations+1) * n);
    magma_malloc( (void **)&activeMask, (n+1) * sizeof(magma_int_t) );

    // === Allocate CPU work space ===
    magma_smalloc_cpu(&condestGhistory, maxIterations+1);
    magma_smalloc_cpu(&gevalues, 3 * n);
    magma_malloc_cpu((void **)&iwork, liwork * sizeof(magma_int_t));

    float *hW;
    magma_smalloc_pinned(&hW, n*n);
    magma_smalloc_pinned(&gevectors, 9*n*n);
    magma_smalloc_pinned(&h_gramB  , 9*n*n);

    // === Allocate GPU workspace ===
    magma_smalloc(&gramM, n * n);
    magma_smalloc(&gramA, 9 * n * n);
    magma_smalloc(&gramB, 9 * n * n);

#if defined(PRECISION_z) || defined(PRECISION_c)
    float *rwork;
    magma_int_t lrwork = 1 + 5*(3*n) + 2*(3*n)*(3*n);

    magma_smalloc_cpu(&rwork, lrwork);
#endif

    // === Set activemask to one ===
    for(int k =0; k<n; k++)
        iwork[k]=1;
    magma_setmatrix(n, 1, sizeof(magma_int_t), iwork, n ,activeMask, n);

    magma_int_t gramDim, ldgram  = 3*n, ikind = 4;

    // === Make the initial vectors orthonormal ===
    magma_sgegqr_gpu(ikind, m, n, blockX, m, dwork, hwork, info );
    //magma_sorthomgs( m, n, blockX );

    magma_s_bspmv_tuned(m, n, c_one, A, blockX, c_zero, blockAX );

    // === Compute the Gram matrix = (X, AX) & its eigenstates ===
    magma_sgemm(MagmaTrans, MagmaNoTrans, n, n, m,
                c_one,  blockX, m, blockAX, m, c_zero, gramM, n);

    magma_ssyevd_gpu( MagmaVec, MagmaUpper,
                      n, gramM, n, evalues, hW, n, hwork, lwork,
#if defined(PRECISION_z) || defined(PRECISION_c)
                      rwork, lrwork,
#endif
                      iwork, liwork, info );

    // === Update  X =  X * evectors ===
    magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                c_one,  blockX, m, gramM, n, c_zero, blockW, m);
    magmablas_swap(blockW, blockX);

    // === Update AX = AX * evectors ===
    magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                c_one,  blockAX, m, gramM, n, c_zero, blockW, m);
    magmablas_swap(blockW, blockAX);

    condestGhistory[1] = 7.82;
    magma_int_t iterationNumber, cBlockSize, restart = 1, iter;

    //Chronometry
    real_Double_t tempo1, tempo2;
    magma_device_sync();
    tempo1=magma_wtime();
    // === Main LOBPCG loop ============================================================
    for(iterationNumber = 1; iterationNumber < maxIterations; iterationNumber++)
    {
        // === compute the residuals (R = Ax - x evalues )
        magmablas_slacpy( MagmaUpperLower, m, n, blockAX, m, blockR, m);

        /*
                    for(int i=0; i<n; i++){
                       magma_saxpy(m, MAGMA_S_MAKE(-evalues[i],0), blockX+i*m, 1, blockR+i*m, 1);
                    }
          */
#if defined(PRECISION_z) || defined(PRECISION_d)
        magma_dsetmatrix( 3*n, 1, evalues, 3*n, eval_gpu, 3*n );
#else
        magma_ssetmatrix( 3*n, 1, evalues, 3*n, eval_gpu, 3*n );
#endif

        magma_slobpcg_res( m, n, eval_gpu, blockX, blockR, eval_gpu);

        magmablas_snrm2_cols(m, n, blockR, m, residualNorms(0, iterationNumber));

        // === remove the residuals corresponding to already converged evectors
        magma_scompact(m, n, blockR, m,
                       residualNorms(0, iterationNumber), residualTolerance,
                       activeMask, &cBlockSize);

        if (cBlockSize == 0)
            break;

        // === apply a preconditioner P to the active residulas: R_new = P R_old
        // === for now set P to be identity (no preconditioner => nothing to be done )
        // magmablas_slacpy( MagmaUpperLower, m, cBlockSize, blockR, m, blockW, m);

        /*
        // === make the preconditioned residuals orthogonal to X
        magma_sgemm(MagmaTrans, MagmaNoTrans, n, cBlockSize, m,
                    c_one, blockX, m, blockR, m, c_zero, gramB(0,0), ldgram);
        magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, cBlockSize, n,
                    c_mone, blockX, m, gramB(0,0), ldgram, c_one, blockR, m);
        */

        // === make the active preconditioned residuals orthonormal
        magma_sgegqr_gpu(ikind, m, cBlockSize, blockR, m, dwork, hwork, info );
        //magma_sorthomgs( m, cBlockSize, blockR );

        // === compute AR
        magma_s_bspmv_tuned(m, cBlockSize, c_one, A, blockR, c_zero, blockAR );

        if (!restart) {
            // === compact P & AP as well
            magma_scompactActive(m, n, blockP,  m, activeMask);
            magma_scompactActive(m, n, blockAP, m, activeMask);

            /*
            // === make P orthogonal to X ?
            magma_sgemm(MagmaTrans, MagmaNoTrans, n, cBlockSize, m,
                        c_one, blockX, m, blockP, m, c_zero, gramB(0,0), ldgram);
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, cBlockSize, n,
                        c_mone, blockX, m, gramB(0,0), ldgram, c_one, blockP, m);

            // === make P orthogonal to R ?
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, cBlockSize, m,
                        c_one, blockR, m, blockP, m, c_zero, gramB(0,0), ldgram);
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, cBlockSize, cBlockSize,
                        c_mone, blockR, m, gramB(0,0), ldgram, c_one, blockP, m);
            */

            // === Make P orthonormal & properly change AP (without multiplication by A)
            magma_sgegqr_gpu(ikind, m, cBlockSize, blockP, m, dwork, hwork, info );
            //magma_sorthomgs( m, cBlockSize, blockP );

            //magma_s_bspmv_tuned(m, cBlockSize, c_one, A, blockP, c_zero, blockAP );
            magma_ssetmatrix( cBlockSize, cBlockSize, hwork, cBlockSize, dwork, cBlockSize);


//                magma_strsm( MagmaRight, MagmaUpper, MagmaNoTrans, MagmaNonUnit,
            //                           m, cBlockSize, c_one, dwork, cBlockSize, blockAP, m);

            // replacement according to Stan
#if defined(PRECISION_s) || defined(PRECISION_d)
            magmablas_strsm( MagmaRight, MagmaUpper, MagmaNoTrans, MagmaNonUnit,
                             m, cBlockSize, c_one, dwork, cBlockSize, blockAP, m);
#else
            magma_strsm( MagmaRight, MagmaUpper, MagmaNoTrans, MagmaNonUnit, m,
                         cBlockSize, c_one, dwork, cBlockSize, blockAP, m);
#endif
        }

        iter = max(1,iterationNumber-10- (int)(log(1.*cBlockSize)));
        float condestGmean = 0.;
        for(int i = 0; i<iterationNumber-iter+1; i++)
            condestGmean += condestGhistory[i];
        condestGmean = condestGmean / (iterationNumber-iter+1);

        if (restart)
            gramDim = n+cBlockSize;
        else
            gramDim = n+2*cBlockSize;

        /* --- The Raileight-Ritz method for [X R P] -----------------------
           [ X R P ]'  [AX  AR  AP] y = evalues [ X R P ]' [ X R P ], i.e.,

                  GramA                                 GramB
            / X'AX  X'AR  X'AP \                 / X'X  X'R  X'P \
           |  R'AX  R'AR  R'AP  | y   = evalues |  R'X  R'R  R'P  |
            \ P'AX  P'AR  P'AP /                 \ P'X  P'R  P'P /
           -----------------------------------------------------------------   */

        // === assemble GramB; first, set it to I
        magmablas_slaset(MagmaFull, ldgram, ldgram, c_zero, c_one, gramB, ldgram);  // identity

        if (!restart) {
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, n, m,
                        c_one, blockP, m, blockX, m, c_zero, gramB(n+cBlockSize,0), ldgram);
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, cBlockSize, m,
                        c_one, blockP, m, blockR, m, c_zero, gramB(n+cBlockSize,n), ldgram);
        }
        magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, n, m,
                    c_one, blockR, m, blockX, m, c_zero, gramB(n,0), ldgram);

        // === get GramB from the GPU to the CPU and compute its eigenvalues only
        magma_sgetmatrix(gramDim, gramDim, gramB, ldgram, h_gramB, ldgram);
        lapackf77_ssyev("N", "L", &gramDim, h_gramB, &ldgram, gevalues,
                        hwork, &lwork,
#if defined(PRECISION_z) || defined(PRECISION_c)
                        rwork,
#endif
                        info);

        // === check stability criteria if we need to restart
        condestG = log10( gevalues[gramDim-1]/gevalues[0] ) + 1.;
        if ((condestG/condestGmean>2 && condestG>2) || condestG>8) {
            // Steepest descent restart for stability
            restart=1;
            printf("restart at step #%d\n", (int) iterationNumber);
        }

        // === assemble GramA; first, set it to I
        magmablas_slaset(MagmaFull, ldgram, ldgram, c_zero, c_one, gramA, ldgram);  // identity

        magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, n, m,
                    c_one, blockR, m, blockAX, m, c_zero, gramA(n,0), ldgram);
        magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, cBlockSize, m,
                    c_one, blockR, m, blockAR, m, c_zero, gramA(n,n), ldgram);

        if (!restart) {
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, n, m,
                        c_one, blockP, m, blockAX, m, c_zero,
                        gramA(n+cBlockSize,0), ldgram);
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, cBlockSize, m,
                        c_one, blockP, m, blockAR, m, c_zero,
                        gramA(n+cBlockSize,n), ldgram);
            magma_sgemm(MagmaTrans, MagmaNoTrans, cBlockSize, cBlockSize, m,
                        c_one, blockP, m, blockAP, m, c_zero,
                        gramA(n+cBlockSize,n+cBlockSize), ldgram);
        }

        /*
        // === Compute X' AX or just use the eigenvalues below ?
        magma_sgemm(MagmaTrans, MagmaNoTrans, n, n, m,
                    c_one, blockX, m, blockAX, m, c_zero,
                    gramA(0,0), ldgram);
        */

        if (restart==0) {
            magma_sgetmatrix(gramDim, gramDim, gramA, ldgram, gevectors, ldgram);
        }
        else {
            gramDim = n+cBlockSize;
            magma_sgetmatrix(gramDim, gramDim, gramA, ldgram, gevectors, ldgram);
        }

        for(int k=0; k<n; k++)
            *gevectors(k,k) = MAGMA_S_MAKE(evalues[k], 0);

        // === the previous eigensolver destroyed what is in h_gramB => must copy it again
        magma_sgetmatrix(gramDim, gramDim, gramB, ldgram, h_gramB, ldgram);

        magma_int_t itype = 1;
        lapackf77_ssygvd(&itype, "V", "L", &gramDim,
                         gevectors, &ldgram, h_gramB, &ldgram,
                         gevalues, hwork, &lwork,
#if defined(PRECISION_z) || defined(PRECISION_c)
                         rwork, &lrwork,
#endif
                         iwork, &liwork, info);

        for(int k =0; k<n; k++)
            evalues[k] = gevalues[k];

        // === copy back the result to gramA on the GPU and use it for the updates
        magma_ssetmatrix(gramDim, gramDim, gevectors, ldgram, gramA, ldgram);

        if (restart == 0) {
            // === contribution from P to the new X (in new search direction P)
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, cBlockSize,
                        c_one, blockP, m, gramA(n+cBlockSize,0), ldgram, c_zero, dwork, m);
            magmablas_swap(dwork, blockP);

            // === contribution from R to the new X (in new search direction P)
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, cBlockSize,
                        c_one, blockR, m, gramA(n,0), ldgram, c_one, blockP, m);

            // === corresponding contribution from AP to the new AX (in AP)
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, cBlockSize,
                        c_one, blockAP, m, gramA(n+cBlockSize,0), ldgram, c_zero, dwork, m);
            magmablas_swap(dwork, blockAP);

            // === corresponding contribution from AR to the new AX (in AP)
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, cBlockSize,
                        c_one, blockAR, m, gramA(n,0), ldgram, c_one, blockAP, m);
        }
        else {
            // === contribution from R (only) to the new X
            magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, cBlockSize,
                        c_one, blockR, m, gramA(n,0), ldgram, c_zero, blockP, m);

            // === corresponding contribution from AR (only) to the new AX
            magma_sgemm(MagmaNoTrans, MagmaNoTrans,m, n, cBlockSize,
                        c_one, blockAR, m, gramA(n,0), ldgram, c_zero, blockAP, m);
        }

        // === contribution from old X to the new X + the new search direction P
        magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                    c_one, blockX, m, gramA, ldgram, c_zero, dwork, m);
        magmablas_swap(dwork, blockX);
        //magma_saxpy(m*n, c_one, blockP, 1, blockX, 1);
        magma_slobpcg_maxpy( m, n, blockP, blockX );


        // === corresponding contribution from old AX to new AX + AP
        magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                    c_one, blockAX, m, gramA, ldgram, c_zero, dwork, m);
        magmablas_swap(dwork, blockAX);
        //magma_saxpy(m*n, c_one, blockAP, 1, blockAX, 1);
        magma_slobpcg_maxpy( m, n, blockAP, blockAX );

        condestGhistory[iterationNumber+1]=condestG;
        if (verbosity==1) {
            // float res;
            // magma_sgetmatrix(1, 1,
            //                  (float*)residualNorms(0, iterationNumber), 1,
            //                  (float*)&res, 1);
            //
            //  printf("Iteration %4d, CBS %4d, Residual: %10.7f\n",
            //         iterationNumber, cBlockSize, res);
            printf("%4d-%2d ", (int) iterationNumber, (int) cBlockSize);
            magma_sprint_gpu(1, n, residualNorms(0, iterationNumber), 1);
        }

        restart = 0;
    }   // === end for iterationNumber = 1,maxIterations =======================


    // fill solver info
    magma_device_sync();
    tempo2=magma_wtime();
    solver_par->runtime = (real_Double_t) tempo2-tempo1;
    solver_par->numiter = iterationNumber;
    if( solver_par->numiter < solver_par->maxiter) {
        solver_par->info = 0;
    } else if( solver_par->init_res > solver_par->final_res )
        solver_par->info = -2;
    else
        solver_par->info = -1;

    // =============================================================================
    // === postprocessing;
    // =============================================================================

    // === compute the real AX and corresponding eigenvalues
    magma_s_bspmv_tuned(m, n, c_one, A, blockX, c_zero, blockAX );
    magma_sgemm(MagmaTrans, MagmaNoTrans, n, n, m,
                c_one,  blockX, m, blockAX, m, c_zero, gramM, n);

    magma_ssyevd_gpu( MagmaVec, MagmaUpper,
                      n, gramM, n, gevalues, dwork, n, hwork, lwork,
#if defined(PRECISION_z) || defined(PRECISION_c)
                      rwork, lrwork,
#endif
                      iwork, liwork, info );

    for(int k =0; k<n; k++)
        evalues[k] = gevalues[k];

    // === update X = X * evectors
    magmablas_swap(blockX, dwork);
    magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                c_one, dwork, m, gramM, n, c_zero, blockX, m);

    // === update AX = AX * evectors to compute the final residual
    magmablas_swap(blockAX, dwork);
    magma_sgemm(MagmaNoTrans, MagmaNoTrans, m, n, n,
                c_one, dwork, m, gramM, n, c_zero, blockAX, m);

    // === compute R = AX - evalues X
    magmablas_slacpy( MagmaUpperLower, m, n, blockAX, m, blockR, m);
    for(int i=0; i<n; i++)
        magma_saxpy(m, MAGMA_S_MAKE(-evalues[i], 0), blockX+i*m, 1, blockR+i*m, 1);

    // === residualNorms[iterationNumber] = || R ||
    magmablas_snrm2_cols(m, n, blockR, m, residualNorms(0, iterationNumber));

    // === restore blockX if needed
    if (blockX != origX)
        magmablas_slacpy( MagmaUpperLower, m, n, blockX, m, origX, m);

    printf("Eigenvalues:\n");
    for(int i =0; i<n; i++)
        printf("%e  ", evalues[i]);
    printf("\n\n");

    printf("Final residuals:\n");
    magma_sprint_gpu(1, n, residualNorms(0, iterationNumber), 1);
    printf("\n\n");

    //=== Print residual history in a file for plotting ====
    float *hresidualNorms;
    magma_smalloc_cpu(&hresidualNorms, (iterationNumber+1) * n);
    magma_sgetmatrix(n, iterationNumber,
                     (float*)residualNorms, n,
                     (float*)hresidualNorms, n);

    printf("Residuals are stored in file residualNorms\n");
    printf("Plot the residuals using: myplot \n");

    FILE *residuals_file;
    residuals_file = fopen("residualNorms", "w");
    for(int i =1; i<iterationNumber; i++) {
        for(int j = 0; j<n; j++)
            fprintf(residuals_file, "%f ", *hresidualNorms(j,i));
        fprintf(residuals_file, "\n");
    }
    fclose(residuals_file);
    magma_free_cpu(hresidualNorms);

    // === free work space
    magma_free(     residualNorms   );
    magma_free_cpu( condestGhistory );
    magma_free_cpu( gevalues        );
    magma_free_cpu( iwork           );

    magma_free_pinned( hW           );
    magma_free_pinned( gevectors    );
    magma_free_pinned( h_gramB      );

    magma_free(     gramM           );
    magma_free(     gramA           );
    magma_free(     gramB           );
    magma_free(  activeMask         );

    magma_free(     blockAX    );
    magma_free(     blockAR    );
    magma_free(     blockAP    );
    magma_free(     blockR    );
    magma_free(     blockP    );
    magma_free(     blockW    );
    magma_free(     dwork    );
    magma_free(     eval_gpu    );

    magma_free_pinned( hwork    );


#if defined(PRECISION_z) || defined(PRECISION_c)
    magma_free_cpu( rwork           );
#endif

    return MAGMA_SUCCESS;
}
コード例 #4
0
/**
    Purpose
    -------
    SSYGVD computes all the eigenvalues, and optionally, the eigenvectors
    of a real generalized symmetric-definite eigenproblem, of the form
    A*x=(lambda)*B*x,  A*Bx=(lambda)*x,  or B*A*x=(lambda)*x.  Here A and
    B are assumed to be symmetric and B is also positive definite.
    If eigenvectors are desired, it uses a divide and conquer algorithm.

    The divide and conquer algorithm makes very mild assumptions about
    floating point arithmetic. It will work on machines with a guard
    digit in add/subtract, or on those binary machines without guard
    digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or
    Cray-2. It could conceivably fail on hexadecimal or decimal machines
    without guard digits, but we know of none.

    Arguments
    ---------
    @param[in]
    itype   INTEGER
            Specifies the problem type to be solved:
            = 1:  A*x = (lambda)*B*x
            = 2:  A*B*x = (lambda)*x
            = 3:  B*A*x = (lambda)*x

    @param[in]
    jobz    magma_vec_t
      -     = MagmaNoVec:  Compute eigenvalues only;
      -     = MagmaVec:    Compute eigenvalues and eigenvectors.

    @param[in]
    uplo    magma_uplo_t
      -     = MagmaUpper:  Upper triangles of A and B are stored;
      -     = MagmaLower:  Lower triangles of A and B are stored.

    @param[in]
    n       INTEGER
            The order of the matrices A and B.  N >= 0.

    @param[in,out]
    A       REAL array, dimension (LDA, N)
            On entry, the symmetric matrix A.  If UPLO = MagmaUpper, the
            leading N-by-N upper triangular part of A contains the
            upper triangular part of the matrix A.  If UPLO = MagmaLower,
            the leading N-by-N lower triangular part of A contains
            the lower triangular part of the matrix A.
    \n
            On exit, if JOBZ = MagmaVec, then if INFO = 0, A contains the
            matrix Z of eigenvectors.  The eigenvectors are normalized
            as follows:
            if ITYPE = 1 or 2, Z**T *   B    * Z = I;
            if ITYPE = 3,      Z**T * inv(B) * Z = I.
            If JOBZ = MagmaNoVec, then on exit the upper triangle (if UPLO=MagmaUpper)
            or the lower triangle (if UPLO=MagmaLower) of A, including the
            diagonal, is destroyed.

    @param[in]
    lda     INTEGER
            The leading dimension of the array A.  LDA >= max(1,N).

    @param[in,out]
    B       REAL array, dimension (LDB, N)
            On entry, the symmetric matrix B.  If UPLO = MagmaUpper, the
            leading N-by-N upper triangular part of B contains the
            upper triangular part of the matrix B.  If UPLO = MagmaLower,
            the leading N-by-N lower triangular part of B contains
            the lower triangular part of the matrix B.
    \n
            On exit, if INFO <= N, the part of B containing the matrix is
            overwritten by the triangular factor U or L from the Cholesky
            factorization B = U**T * U or B = L * L**T.

    @param[in]
    ldb     INTEGER
            The leading dimension of the array B.  LDB >= max(1,N).

    @param[out]
    w       REAL array, dimension (N)
            If INFO = 0, the eigenvalues in ascending order.

    @param[out]
    work    (workspace) REAL array, dimension (MAX(1,LWORK))
            On exit, if INFO = 0, WORK[0] returns the optimal LWORK.

    @param[in]
    lwork   INTEGER
            The length of the array WORK.
            If N <= 1,                      LWORK >= 1.
            If JOBZ = MagmaNoVec and N > 1, LWORK >= 2*N + N*NB.
            If JOBZ = MagmaVec   and N > 1, LWORK >= max( 2*N + N*NB, 1 + 6*N + 2*N**2 ).
            NB can be obtained through magma_get_ssytrd_nb(N).
    \n
            If LWORK = -1, then a workspace query is assumed; the routine
            only calculates the optimal sizes of the WORK and IWORK
            arrays, returns these values as the first entries of the WORK
            and IWORK arrays, and no error message related to LWORK or
            LIWORK is issued by XERBLA.

    @param[out]
    iwork   (workspace) INTEGER array, dimension (MAX(1,LIWORK))
            On exit, if INFO = 0, IWORK[0] returns the optimal LIWORK.

    @param[in]
    liwork  INTEGER
            The dimension of the array IWORK.
            If N <= 1,                      LIWORK >= 1.
            If JOBZ = MagmaNoVec and N > 1, LIWORK >= 1.
            If JOBZ = MagmaVec   and N > 1, LIWORK >= 3 + 5*N.
    \n
            If LIWORK = -1, then a workspace query is assumed; the
            routine only calculates the optimal sizes of the WORK and
            IWORK arrays, returns these values as the first entries of
            the WORK and IWORK arrays, and no error message related to
            LWORK or LIWORK is issued by XERBLA.

    @param[out]
    info    INTEGER
      -     = 0:  successful exit
      -     < 0:  if INFO = -i, the i-th argument had an illegal value
      -     > 0:  SPOTRF or SSYEVD returned an error code:
               <= N:  if INFO = i and JOBZ = MagmaNoVec, then the algorithm
                      failed to converge; i off-diagonal elements of an
                      intermediate tridiagonal form did not converge to
                      zero;
                      if INFO = i and JOBZ = MagmaVec, then the algorithm
                      failed to compute an eigenvalue while working on
                      the submatrix lying in rows and columns INFO/(N+1)
                      through mod(INFO,N+1);
               > N:   if INFO = N + i, for 1 <= i <= N, then the leading
                      minor of order i of B is not positive definite.
                      The factorization of B could not be completed and
                      no eigenvalues or eigenvectors were computed.

    Further Details
    ---------------
    Based on contributions by
       Mark Fahey, Department of Mathematics, Univ. of Kentucky, USA

    Modified so that no backsubstitution is performed if SSYEVD fails to
    converge (NEIG in old code could be greater than N causing out of
    bounds reference to A - reported by Ralf Meyer).  Also corrected the
    description of INFO and the test on ITYPE. Sven, 16 Feb 05.

    @ingroup magma_ssygv_driver
    ********************************************************************/
extern "C" magma_int_t
magma_ssygvd(
    magma_int_t itype, magma_vec_t jobz, magma_uplo_t uplo, magma_int_t n,
    float *A, magma_int_t lda,
    float *B, magma_int_t ldb,
    float *w,
    float *work, magma_int_t lwork,
    #ifdef COMPLEX
    float *rwork, magma_int_t lrwork,
    #endif
    magma_int_t *iwork, magma_int_t liwork,
    magma_int_t *info)
{
    const char* uplo_ = lapack_uplo_const( uplo );
    const char* jobz_ = lapack_vec_const( jobz );

    float d_one = MAGMA_S_ONE;

    float *dA=NULL, *dB=NULL;
    magma_int_t ldda = magma_roundup( n, 32 );
    magma_int_t lddb = ldda;

    magma_int_t lower;
    magma_trans_t trans;
    magma_int_t wantz, lquery;

    magma_int_t lwmin, liwmin;

    wantz = (jobz == MagmaVec);
    lower = (uplo == MagmaLower);
    lquery = (lwork == -1 || liwork == -1);

    *info = 0;
    if (itype < 1 || itype > 3) {
        *info = -1;
    } else if (! (wantz || (jobz == MagmaNoVec))) {
        *info = -2;
    } else if (! (lower || (uplo == MagmaUpper))) {
        *info = -3;
    } else if (n < 0) {
        *info = -4;
    } else if (lda < max(1,n)) {
        *info = -6;
    } else if (ldb < max(1,n)) {
        *info = -8;
    }

    magma_int_t nb = magma_get_ssytrd_nb( n );
    if ( n <= 1 ) {
        lwmin  = 1;
        liwmin = 1;
    }
    else if ( wantz ) {
        lwmin  = max( 2*n + n*nb, 1 + 6*n + 2*n*n );
        liwmin = 3 + 5*n;
    }
    else {
        lwmin  = 2*n + n*nb;
        liwmin = 1;
    }
    
    work[0]  = magma_smake_lwork( lwmin );
    iwork[0] = liwmin;

    if (lwork < lwmin && ! lquery) {
        *info = -11;
    } else if (liwork < liwmin && ! lquery) {
        *info = -13;
    }

    if (*info != 0) {
        magma_xerbla( __func__, -(*info) );
        return *info;
    }
    else if (lquery) {
        return *info;
    }

    /* Quick return if possible */
    if (n == 0) {
        return *info;
    }
    
    /* If matrix is very small, then just call LAPACK on CPU, no need for GPU */
    if (n <= 128) {
        lapackf77_ssygvd( &itype, jobz_, uplo_,
                          &n, A, &lda, B, &ldb,
                          w, work, &lwork,
                          iwork, &liwork, info );
        return *info;
    }

    if (MAGMA_SUCCESS != magma_smalloc( &dA, n*ldda ) ||
        MAGMA_SUCCESS != magma_smalloc( &dB, n*lddb )) {
        magma_free( dA );
        magma_free( dB );
        *info = MAGMA_ERR_DEVICE_ALLOC;
        return *info;
    }

    magma_queue_t queue;
    magma_device_t cdev;
    magma_getdevice( &cdev );
    magma_queue_create( cdev, &queue );

    /* Form a Cholesky factorization of B. */
    magma_ssetmatrix( n, n, B, ldb, dB, lddb, queue );
    magma_ssetmatrix_async( n, n,
                            A,  lda,
                            dA, ldda, queue );

    magma_timer_t time=0;
    timer_start( time );
    magma_spotrf_gpu( uplo, n, dB, lddb, info );
    if (*info != 0) {
        *info = n + *info;
        return *info;
    }
    timer_stop( time );
    timer_printf( "time spotrf_gpu = %6.2f\n", time );

    magma_queue_sync( queue );
    magma_sgetmatrix_async( n, n,
                            dB, lddb,
                            B,  ldb, queue );

    timer_start( time );
    /* Transform problem to standard eigenvalue problem and solve. */
    magma_ssygst_gpu( itype, uplo, n, dA, ldda, dB, lddb, info );
    timer_stop( time );
    timer_printf( "time ssygst_gpu = %6.2f\n", time );

    /* simple fix to be able to run bigger size.
     * set dB=NULL so we know to re-allocate below
     * TODO: have dwork here that will be used as dB and then passed to  ssyevd.
     */
    if (n > 5000) {
        magma_queue_sync( queue );
        magma_free( dB );  dB=NULL;
    }

    timer_start( time );
    magma_ssyevd_gpu( jobz, uplo, n, dA, ldda, w, A, lda,
                      work, lwork, iwork, liwork, info );
    timer_stop( time );
    timer_printf( "time ssyevd_gpu = %6.2f\n", time );

    if (wantz && *info == 0) {
        timer_start( time );
        
        /* allocate and copy dB back */
        if (dB == NULL) {
            if (MAGMA_SUCCESS != magma_smalloc( &dB, n*lddb ) ) {
                magma_free( dA );
                *info = MAGMA_ERR_DEVICE_ALLOC;
                return *info;
            }
            magma_ssetmatrix( n, n, B, ldb, dB, lddb, queue );
        }
        /* Backtransform eigenvectors to the original problem. */
        if (itype == 1 || itype == 2) {
            /* For A*x=(lambda)*B*x and A*B*x=(lambda)*x;
               backtransform eigenvectors: x = inv(L)'*y or inv(U)*y */
            if (lower) {
                trans = MagmaTrans;
            } else {
                trans = MagmaNoTrans;
            }
            magma_strsm( MagmaLeft, uplo, trans, MagmaNonUnit,
                         n, n, d_one, dB, lddb, dA, ldda, queue );
        }
        else if (itype == 3) {
            /* For B*A*x=(lambda)*x;
               backtransform eigenvectors: x = L*y or U'*y */
            if (lower) {
                trans = MagmaNoTrans;
            } else {
                trans = MagmaTrans;
            }
            magma_strmm( MagmaLeft, uplo, trans, MagmaNonUnit,
                         n, n, d_one, dB, lddb, dA, ldda, queue );
        }
        magma_sgetmatrix( n, n, dA, ldda, A, lda, queue );
        
        timer_stop( time );
        timer_printf( "time strsm/mm + getmatrix = %6.2f\n", time );
    }

    magma_queue_sync( queue );
    magma_queue_destroy( queue );

    work[0]  = magma_smake_lwork( lwmin );
    iwork[0] = liwmin;

    magma_free( dA );  dA=NULL;
    magma_free( dB );  dB=NULL;

    return *info;
} /* magma_ssygvd */