Esempio n. 1
0
/* ////////////////////////////////////////////////////////////////////////////
   -- Testing dgetrf
*/
int main( int argc, char** argv )
{
    TESTING_INIT();

    real_Double_t   gflops, gpu_perf, gpu_time, cpu_perf, cpu_time;
    double *h_A, *h_R, *work;
    magmaDouble_ptr d_A, dwork;
    double c_neg_one = MAGMA_D_NEG_ONE;
    magma_int_t N, n2, lda, ldda, info, lwork, ldwork;
    magma_int_t ione     = 1;
    magma_int_t ISEED[4] = {0,0,0,1};
    double tmp;
    double error, rwork[1];
    magma_int_t *ipiv;
    magma_int_t status = 0;
    
    magma_opts opts;
    parse_opts( argc, argv, &opts );
    opts.lapack |= opts.check;  // check (-c) implies lapack (-l)
    
    // need looser bound (3000*eps instead of 30*eps) for tests
    // TODO: should compute ||I - A*A^{-1}|| / (n*||A||*||A^{-1}||)
    opts.tolerance = max( 3000., opts.tolerance );
    double tol = opts.tolerance * lapackf77_dlamch("E");
    
    printf("    N   CPU GFlop/s (sec)   GPU GFlop/s (sec)   ||R||_F / (N*||A||_F)\n");
    printf("=================================================================\n");
    for( int itest = 0; itest < opts.ntest; ++itest ) {
        for( int iter = 0; iter < opts.niter; ++iter ) {
            N = opts.nsize[itest];
            lda    = N;
            n2     = lda*N;
            ldda   = ((N+31)/32)*32;
            ldwork = N * magma_get_dgetri_nb( N );
            gflops = FLOPS_DGETRI( N ) / 1e9;
            
            // query for workspace size
            lwork = -1;
            lapackf77_dgetri( &N, NULL, &lda, NULL, &tmp, &lwork, &info );
            if (info != 0)
                printf("lapackf77_dgetri returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            lwork = int( MAGMA_D_REAL( tmp ));
            
            TESTING_MALLOC_CPU( ipiv,  magma_int_t,        N      );
            TESTING_MALLOC_CPU( work,  double, lwork  );
            TESTING_MALLOC_CPU( h_A,   double, n2     );
            
            TESTING_MALLOC_PIN( h_R,   double, n2     );
            
            TESTING_MALLOC_DEV( d_A,   double, ldda*N );
            TESTING_MALLOC_DEV( dwork, double, ldwork );
            
            /* Initialize the matrix */
            lapackf77_dlarnv( &ione, ISEED, &n2, h_A );
            error = lapackf77_dlange( "f", &N, &N, h_A, &lda, rwork );  // norm(A)
            
            /* Factor the matrix. Both MAGMA and LAPACK will use this factor. */
            magma_dsetmatrix( N, N, h_A, lda, d_A, 0, ldda, opts.queue );
            magma_dgetrf_gpu( N, N, d_A, 0, ldda, ipiv, opts.queue, &info );
            magma_dgetmatrix( N, N, d_A, 0, ldda, h_A, lda, opts.queue );
            if ( info != 0 )
                printf("magma_dgetrf_gpu returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            
            // check for exact singularity
            //h_A[ 10 + 10*lda ] = MAGMA_D_MAKE( 0.0, 0.0 );
            //magma_dsetmatrix( N, N, h_A, lda, d_A, 0, ldda, opts.queue );
            
            /* ====================================================================
               Performs operation using MAGMA
               =================================================================== */
            gpu_time = magma_wtime();
            magma_dgetri_gpu( N, d_A, 0, ldda, ipiv, dwork, 0, ldwork, opts.queues2, &info );
            gpu_time = magma_wtime() - gpu_time;
            gpu_perf = gflops / gpu_time;
            if (info != 0)
                printf("magma_dgetri_gpu returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            
            magma_dgetmatrix( N, N, d_A, 0, ldda, h_R, lda, opts.queue );
            
            /* =====================================================================
               Performs operation using LAPACK
               =================================================================== */
            if ( opts.lapack ) {
                cpu_time = magma_wtime();
                lapackf77_dgetri( &N, h_A, &lda, ipiv, work, &lwork, &info );
                cpu_time = magma_wtime() - cpu_time;
                cpu_perf = gflops / cpu_time;
                if (info != 0)
                    printf("lapackf77_dgetri returned error %d: %s.\n",
                           (int) info, magma_strerror( info ));
                
                /* =====================================================================
                   Check the result compared to LAPACK
                   =================================================================== */
                blasf77_daxpy( &n2, &c_neg_one, h_A, &ione, h_R, &ione );
                error = lapackf77_dlange( "f", &N, &N, h_R, &lda, rwork ) / (N*error);
                
                printf( "%5d   %7.2f (%7.2f)   %7.2f (%7.2f)   %8.2e   %s\n",
                        (int) N, cpu_perf, cpu_time, gpu_perf, gpu_time,
                        error, (error < tol ? "ok" : "failed"));
                status += ! (error < tol);
            }
            else {
                printf( "%5d     ---   (  ---  )   %7.2f (%7.2f)     ---\n",
                        (int) N, gpu_perf, gpu_time );
            }
            
            TESTING_FREE_CPU( ipiv  );
            TESTING_FREE_CPU( work  );
            TESTING_FREE_CPU( h_A   );
            
            TESTING_FREE_PIN( h_R   );
            
            TESTING_FREE_DEV( d_A   );
            TESTING_FREE_DEV( dwork );
            fflush( stdout );
        }
        if ( opts.niter > 1 ) {
            printf( "\n" );
        }
    }

    TESTING_FINALIZE();
    return status;
}
Esempio n. 2
0
/* ////////////////////////////////////////////////////////////////////////////
   -- Testing dgetri
*/
int main( int argc, char** argv )
{
    TESTING_INIT();

    // constants
    const double c_zero    = MAGMA_D_ZERO;
    const double c_one     = MAGMA_D_ONE;
    const double c_neg_one = MAGMA_D_NEG_ONE;
    
    real_Double_t   gflops, gpu_perf, gpu_time, cpu_perf, cpu_time;
    double *h_A, *h_Ainv, *h_R, *work;
    magmaDouble_ptr d_A, dwork;
    magma_int_t N, n2, lda, ldda, info, lwork, ldwork;
    magma_int_t ione     = 1;
    magma_int_t ISEED[4] = {0,0,0,1};
    double tmp;
    double error, rwork[1];
    magma_int_t *ipiv;
    magma_int_t status = 0;
    
    magma_opts opts;
    opts.parse_opts( argc, argv );
    
    double tol = opts.tolerance * lapackf77_dlamch("E");
    
    printf("%%   N   CPU Gflop/s (sec)   GPU Gflop/s (sec)   ||I - A*A^{-1}||_1 / (N*cond(A))\n");
    printf("%%===============================================================================\n");
    for( int itest = 0; itest < opts.ntest; ++itest ) {
        for( int iter = 0; iter < opts.niter; ++iter ) {
            N = opts.nsize[itest];
            lda    = N;
            n2     = lda*N;
            ldda   = magma_roundup( N, opts.align );  // multiple of 32 by default
            ldwork = N * magma_get_dgetri_nb( N );
            gflops = FLOPS_DGETRI( N ) / 1e9;
            
            // query for workspace size
            lwork = -1;
            lapackf77_dgetri( &N, NULL, &lda, NULL, &tmp, &lwork, &info );
            if (info != 0) {
                printf("lapackf77_dgetri returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            }
            lwork = magma_int_t( MAGMA_D_REAL( tmp ));
            
            TESTING_MALLOC_CPU( ipiv,   magma_int_t,        N      );
            TESTING_MALLOC_CPU( work,   double, lwork  );
            TESTING_MALLOC_CPU( h_A,    double, n2     );
            TESTING_MALLOC_CPU( h_Ainv, double, n2     );
            TESTING_MALLOC_CPU( h_R,    double, n2     );
            
            TESTING_MALLOC_DEV( d_A,    double, ldda*N );
            TESTING_MALLOC_DEV( dwork,  double, ldwork );
            
            /* Initialize the matrix */
            lapackf77_dlarnv( &ione, ISEED, &n2, h_A );
            
            /* Factor the matrix. Both MAGMA and LAPACK will use this factor. */
            magma_dsetmatrix( N, N, h_A, lda, d_A, ldda, opts.queue );
            magma_dgetrf_gpu( N, N, d_A, ldda, ipiv, &info );
            magma_dgetmatrix( N, N, d_A, ldda, h_Ainv, lda, opts.queue );
            if (info != 0) {
                printf("magma_dgetrf_gpu returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            }
            
            // check for exact singularity
            //h_Ainv[ 10 + 10*lda ] = MAGMA_D_MAKE( 0.0, 0.0 );
            //magma_dsetmatrix( N, N, h_Ainv, lda, d_A, ldda, opts.queue );
            
            /* ====================================================================
               Performs operation using MAGMA
               =================================================================== */
            gpu_time = magma_wtime();
            magma_dgetri_gpu( N, d_A, ldda, ipiv, dwork, ldwork, &info );
            gpu_time = magma_wtime() - gpu_time;
            gpu_perf = gflops / gpu_time;
            if (info != 0) {
                printf("magma_dgetri_gpu returned error %d: %s.\n",
                       (int) info, magma_strerror( info ));
            }
            
            /* =====================================================================
               Performs operation using LAPACK
               =================================================================== */
            if ( opts.lapack ) {
                cpu_time = magma_wtime();
                lapackf77_dgetri( &N, h_Ainv, &lda, ipiv, work, &lwork, &info );
                cpu_time = magma_wtime() - cpu_time;
                cpu_perf = gflops / cpu_time;
                if (info != 0) {
                    printf("lapackf77_dgetri returned error %d: %s.\n",
                           (int) info, magma_strerror( info ));
                }
                printf( "%5d   %7.2f (%7.2f)   %7.2f (%7.2f)",
                        (int) N, cpu_perf, cpu_time, gpu_perf, gpu_time );
            }
            else {
                printf( "%5d     ---   (  ---  )   %7.2f (%7.2f)",
                        (int) N, gpu_perf, gpu_time );
            }
            
            /* =====================================================================
               Check the result
               =================================================================== */
            if ( opts.check ) {
                magma_dgetmatrix( N, N, d_A, ldda, h_Ainv, lda, opts.queue );
                
                // compute 1-norm condition number estimate, following LAPACK's zget03
                double normA, normAinv, rcond;
                normA    = lapackf77_dlange( "1", &N, &N, h_A,    &lda, rwork );
                normAinv = lapackf77_dlange( "1", &N, &N, h_Ainv, &lda, rwork );
                if ( normA <= 0 || normAinv <= 0 ) {
                    rcond = 0;
                    error = 1 / (tol/opts.tolerance);  // == 1/eps
                }
                else {
                    rcond = (1 / normA) / normAinv;
                    // R = I
                    // R -= A*A^{-1}
                    // err = ||I - A*A^{-1}|| / ( N ||A||*||A^{-1}|| ) = ||R|| * rcond / N, using 1-norm
                    lapackf77_dlaset( "full", &N, &N, &c_zero, &c_one, h_R, &lda );
                    blasf77_dgemm( "no", "no", &N, &N, &N,
                                   &c_neg_one, h_A,    &lda,
                                               h_Ainv, &lda,
                                   &c_one,     h_R,    &lda );
                    error = lapackf77_dlange( "1", &N, &N, h_R, &lda, rwork );
                    error = error * rcond / N;
                }
                
                bool okay = (error < tol);
                status += ! okay;
                printf( "   %8.2e   %s\n",
                        error, (okay ? "ok" : "failed"));
            }
            else {
                printf( "\n" );
            }
            
            TESTING_FREE_CPU( ipiv   );
            TESTING_FREE_CPU( work   );
            TESTING_FREE_CPU( h_A    );
            TESTING_FREE_CPU( h_Ainv );
            TESTING_FREE_CPU( h_R    );
            
            TESTING_FREE_DEV( d_A    );
            TESTING_FREE_DEV( dwork  );
            fflush( stdout );
        }
        if ( opts.niter > 1 ) {
            printf( "\n" );
        }
    }

    opts.cleanup();
    TESTING_FINALIZE();
    return status;
}
Esempio n. 3
0
magma_int_t magmaf_get_dgetri_nb( magma_int_t *m )
{
    return magma_get_dgetri_nb( *m );
}
Esempio n. 4
0
extern "C" magma_int_t
magma_dgetri_gpu( magma_int_t n, double *dA, magma_int_t lda,
                  magma_int_t *ipiv, double *dwork, magma_int_t lwork,
                  magma_int_t *info )
{
/*  -- MAGMA (version 1.3.0) --
       Univ. of Tennessee, Knoxville
       Univ. of California, Berkeley
       Univ. of Colorado, Denver
       November 2012

    Purpose
    =======

        DGETRI computes the inverse of a matrix using the LU factorization
        computed by DGETRF. This method inverts U and then computes inv(A) by
        solving the system inv(A)*L = inv(U) for inv(A).
        
        Note that it is generally both faster and more accurate to use DGESV,
        or DGETRF and DGETRS, to solve the system AX = B, rather than inverting
        the matrix and multiplying to form X = inv(A)*B. Only in special
        instances should an explicit inverse be computed with this routine.

    Arguments
    =========

        N       (input) INTEGER
                The order of the matrix A.  N >= 0.

        dA      (input/output) DOUBLE_PRECISION array on the GPU, dimension (LDA,N)
                On entry, the factors L and U from the factorization
                A = P*L*U as computed by DGETRF_GPU.
                On exit, if INFO = 0, the inverse of the original matrix A.

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

        IPIV    (input) INTEGER array, dimension (N)
                The pivot indices from DGETRF; for 1<=i<=N, row i of the
                matrix was interchanged with row IPIV(i).

        DWORK    (workspace/output) COMPLEX*16 array on the GPU, dimension (MAX(1,LWORK))
      
        LWORK   (input) INTEGER
                The dimension of the array DWORK.  LWORK >= N*NB, where NB is
                the optimal blocksize returned by magma_get_dgetri_nb(n).
                
                Unlike LAPACK, this version does not currently support a
                workspace query, because the workspace is on the GPU.

        INFO    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -i, the i-th argument had an illegal value
                > 0:  if INFO = i, U(i,i) is exactly zero; the matrix is
                      singular and its cannot be computed.

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

    /* Local variables */
    double c_one     = MAGMA_D_ONE;
    double c_neg_one = MAGMA_D_NEG_ONE;
    double *dL = dwork;
    magma_int_t     ldl = n;
    magma_int_t      nb = magma_get_dgetri_nb(n);
    magma_int_t j, jmax, jb, jp;
    
    *info = 0;
    if (n < 0)
        *info = -1;
    else if (lda < max(1,n))
        *info = -3;
    else if ( lwork < n*nb )
        *info = -6;

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

    /* Quick return if possible */
    if ( n == 0 )
        return *info;
    
    /* Invert the triangular factor U */
    magma_dtrtri_gpu( MagmaUpper, MagmaNonUnit, n, dA, lda, info );
    if ( *info != 0 )
        return *info;
    
    jmax = ((n-1) / nb)*nb;
    for( j = jmax; j >= 0; j -= nb ) {
        jb = min( nb, n-j );
        
        // copy current block column of L to work space,
        // then replace with zeros in A.
        magmablas_dlacpy( MagmaUpperLower, n-j, jb,
                          &dA[j + j*lda], lda,
                          &dL[j        ], ldl );
        magmablas_dlaset( MagmaLower, n-j, jb, &dA[j + j*lda], lda );
        
        // compute current block column of Ainv
        // Ainv(:, j:j+jb-1)
        //   = ( U(:, j:j+jb-1) - Ainv(:, j+jb:n) L(j+jb:n, j:j+jb-1) )
        //   * L(j:j+jb-1, j:j+jb-1)^{-1}
        // where L(:, j:j+jb-1) is stored in dL.
        if ( j+jb < n ) {
            magma_dgemm( MagmaNoTrans, MagmaNoTrans, n, jb, n-j-jb,
                         c_neg_one, &dA[(j+jb)*lda], lda,
                                    &dL[ j+jb     ], ldl,
                         c_one,     &dA[     j*lda], lda );
        }
        magma_dtrsm( MagmaRight, MagmaLower, MagmaNoTrans, MagmaUnit,
                     n, jb, c_one,
                     &dL[j    ], ldl,
                     &dA[j*lda], lda );
    }

    // Apply column interchanges
    for( j = n-2; j >= 0; --j ) {
        jp = ipiv[j] - 1;
        if ( jp != j ) {
            magmablas_dswap( n, &dA[ j*lda ], 1, &dA[ jp*lda ], 1 );
        }
    }
    
    return *info;
}
Esempio n. 5
0
SEXP magma_dgeMatrix_solve(SEXP a)
{
#ifdef HIPLAR_WITH_MAGMA
    /*  compute the 1-norm of the matrix, which is needed
	later for the computation of the reciprocal condition number. */
    double aNorm = magma_get_norm(a, "1");

    /* the LU decomposition : */
		/* Given that we may be performing this operation
		 * on the GPU we may put in an optimisation here
		 * where if we call the LU solver we, we do not require
		 * the decomposition to be transferred back to CPU. This is TODO
		 */
    SEXP val = PROTECT(NEW_OBJECT(MAKE_CLASS("dgeMatrix"))),
	lu = magma_dgeMatrix_LU_(a, TRUE);
    int *dims = INTEGER(GET_SLOT(lu, Matrix_DimSym)),
	*pivot = INTEGER(GET_SLOT(lu, Matrix_permSym));

    /* prepare variables for the dgetri calls */
    double *x, tmp;
    int	info, lwork = -1;

    if (dims[0] != dims[1]) error(_("Solve requires a square matrix"));
    slot_dup(val, lu, Matrix_xSym);
    x = REAL(GET_SLOT(val, Matrix_xSym));
    slot_dup(val, lu, Matrix_DimSym);
		int N2 = dims[0] * dims[0];

    if(dims[0]) /* the dimension is not zero */
    {
			/* is the matrix is *computationally* singular ? */
			double rcond;
			F77_CALL(dgecon)("1", dims, x, dims, &aNorm, &rcond,
					(double *) R_alloc(4*dims[0], sizeof(double)),
					(int *) R_alloc(dims[0], sizeof(int)), &info);
			if (info)
				error(_("error [%d] from Lapack 'dgecon()'"), info);
			if(rcond < DOUBLE_EPS)
				error(_("Lapack dgecon(): system computationally singular, reciprocal condition number = %g"),
						rcond);

			/* only now try the inversion and check if the matrix is *exactly* singular: */
			// This is also a work space query. This is not an option in magma

			F77_CALL(dgetri)(dims, x, dims, pivot, &tmp, &lwork, &info);
			lwork = (int) tmp;
			
			if( GPUFlag == 0){
				

				F77_CALL(dgetri)(dims, x, dims, pivot,
						(double *) R_alloc((size_t) lwork, sizeof(double)),
						&lwork, &info);

#ifdef HIPLAR_DBG
				R_ShowMessage("DBG: Solve using LU using dgetri;");
#endif
			}
			else if(GPUFlag == 1) {
				
				double *d_x, *dwork; 
				cublasStatus retStatus;			
	
#ifdef HIPLAR_DBG
				R_ShowMessage("Solve using LU using magma_dgetri;");
#endif
				cublasAlloc(N2, sizeof(double), (void**)&d_x);

				//cublasAlloc(N2 , sizeof(double), (void**)&dtmp);
				/* Error Checking */
				retStatus = cublasGetError ();
				if (retStatus != CUBLAS_STATUS_SUCCESS) 
					error(_("CUBLAS: Error in Memory Allocation on Device"));
				/********************************************/

				cublasSetVector( N2, sizeof(double), x, 1, d_x, 1);

				/* Error Checking */
				retStatus = cublasGetError ();
				if (retStatus != CUBLAS_STATUS_SUCCESS) 
					error(_("CUBLAS: Error in Data Transfer to Device"));
				/********************************************/
				lwork = dims[0] * magma_get_dgetri_nb( dims[0] );
				
					cublasAlloc(lwork, sizeof(double), (void**)&dwork);

				/* Error Checking */
				retStatus = cublasGetError ();
				if (retStatus != CUBLAS_STATUS_SUCCESS) 
					error(_("CUBLAS: Error in Memory Allocation on Device"));
				/********************************************/

				magma_dgetri_gpu(dims[0], d_x, dims[0], pivot, dwork , lwork, &info);

				cublasGetVector(N2, sizeof(double), d_x, 1, x, 1);

				/* Error Checking */
				retStatus = cublasGetError ();
				if (retStatus != CUBLAS_STATUS_SUCCESS) 
					error(_("CUBLAS: Error in Data From to Device"));
				/********************************************/

				cublasFree(dwork);
				cublasFree(d_x);

				/* Error Checking */
				retStatus = cublasGetError ();
				if (retStatus != CUBLAS_STATUS_SUCCESS) 
					error(_("CUBLAS: Error freeing memory"));
				/********************************************/
					
			}
			else
				error(_("GPUFlag not set correctly"));

			if (info)
				error(_("Lapack routine dgetri: system is exactly singular"));
    }
    UNPROTECT(1);
    return val;
#endif
	    return R_NilValue;
}
Esempio n. 6
0
/**
    Purpose
    -------
    DGETRI computes the inverse of a matrix using the LU factorization
    computed by DGETRF. This method inverts U and then computes inv(A) by
    solving the system inv(A)*L = inv(U) for inv(A).
    
    Note that it is generally both faster and more accurate to use DGESV,
    or DGETRF and DGETRS, to solve the system AX = B, rather than inverting
    the matrix and multiplying to form X = inv(A)*B. Only in special
    instances should an explicit inverse be computed with this routine.

    Arguments
    ---------
    @param[in]
    n       INTEGER
            The order of the matrix A.  N >= 0.

    @param[in,out]
    dA      DOUBLE_PRECISION array on the GPU, dimension (LDDA,N)
            On entry, the factors L and U from the factorization
            A = P*L*U as computed by DGETRF_GPU.
            On exit, if INFO = 0, the inverse of the original matrix A.

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

    @param[in]
    ipiv    INTEGER array, dimension (N)
            The pivot indices from DGETRF; for 1 <= i <= N, row i of the
            matrix was interchanged with row IPIV(i).

    @param[out]
    dwork   (workspace) DOUBLE_PRECISION array on the GPU, dimension (MAX(1,LWORK))
  
    @param[in]
    lwork   INTEGER
            The dimension of the array DWORK.  LWORK >= N*NB, where NB is
            the optimal blocksize returned by magma_get_dgetri_nb(n).
    \n
            Unlike LAPACK, this version does not currently support a
            workspace query, because the workspace is on the GPU.

    @param[out]
    info    INTEGER
      -     = 0:  successful exit
      -     < 0:  if INFO = -i, the i-th argument had an illegal value
      -     > 0:  if INFO = i, U(i,i) is exactly zero; the matrix is
                  singular and its cannot be computed.

    @ingroup magma_dgesv_comp
    ********************************************************************/
extern "C" magma_int_t
magma_dgetri_gpu( magma_int_t n, double *dA, magma_int_t ldda,
                  magma_int_t *ipiv, double *dwork, magma_int_t lwork,
                  magma_int_t *info )
{
    #define dA(i, j)  (dA + (i) + (j)*ldda)
    #define dL(i, j)  (dL + (i) + (j)*lddl)
    
    /* Local variables */
    double c_zero    = MAGMA_D_ZERO;
    double c_one     = MAGMA_D_ONE;
    double c_neg_one = MAGMA_D_NEG_ONE;
    double *dL = dwork;
    magma_int_t lddl = n;
    magma_int_t nb   = magma_get_dgetri_nb(n);
    magma_int_t j, jmax, jb, jp;
    
    *info = 0;
    if (n < 0)
        *info = -1;
    else if (ldda < max(1,n))
        *info = -3;
    else if ( lwork < n*nb )
        *info = -6;

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

    /* Quick return if possible */
    if ( n == 0 )
        return *info;
    
    /* Invert the triangular factor U */
    magma_dtrtri_gpu( MagmaUpper, MagmaNonUnit, n, dA, ldda, info );
    if ( *info != 0 )
        return *info;
    
    jmax = ((n-1) / nb)*nb;
    for( j = jmax; j >= 0; j -= nb ) {
        jb = min( nb, n-j );
        
        // copy current block column of A to work space dL
        // (only needs lower trapezoid, but we also copy upper triangle),
        // then zero the strictly lower trapezoid block column of A.
        magmablas_dlacpy( MagmaFull, n-j, jb,
                          dA(j,j), ldda,
                          dL(j,0), lddl );
        magmablas_dlaset( MagmaLower, n-j-1, jb, c_zero, c_zero, dA(j+1,j), ldda );
        
        // compute current block column of Ainv
        // Ainv(:, j:j+jb-1)
        //   = ( U(:, j:j+jb-1) - Ainv(:, j+jb:n) L(j+jb:n, j:j+jb-1) )
        //   * L(j:j+jb-1, j:j+jb-1)^{-1}
        // where L(:, j:j+jb-1) is stored in dL.
        if ( j+jb < n ) {
            magma_dgemm( MagmaNoTrans, MagmaNoTrans, n, jb, n-j-jb,
                         c_neg_one, dA(0,j+jb), ldda,
                                    dL(j+jb,0), lddl,
                         c_one,     dA(0,j),    ldda );
        }
        // TODO use magmablas work interface
        magma_dtrsm( MagmaRight, MagmaLower, MagmaNoTrans, MagmaUnit,
                     n, jb, c_one,
                     dL(j,0), lddl,
                     dA(0,j), ldda );
    }

    // Apply column interchanges
    for( j = n-2; j >= 0; --j ) {
        jp = ipiv[j] - 1;
        if ( jp != j ) {
            magmablas_dswap( n, dA(0,j), 1, dA(0,jp), 1 );
        }
    }
    
    return *info;
}