Esempio n. 1
0
    def sensitivity(self, dp_var_data, state_ap, select=None):
        """
        Sensitivity of objective function evaluation for given direct
        and adjoint problem states.
        """
        apb = self.apb

        var_data = state_ap.get_parts()
        var_data.update(dp_var_data)

        self.ofg_equations.set_data(var_data, ignore_unknown=True)

        dim = self.sp_boxes.dim
        n_mesh_nod = apb.domain.shape.n_nod

        if select is None:
            idsgs = nm.arange(self.dsg_vars.n_dsg, dtype=nm.int32)
        else:
            idsgs = select

        sa = []

        pbar = MyBar('sensitivity:')
        pbar.init(len(idsgs))

        shape = (n_mesh_nod, dim)
        for ii, nu in enumerate(self.generate_mesh_velocity(shape, idsgs)):
            pbar.update(ii)
            self.ofg_variables['Nu'].data_from_any(nu.ravel())

            ## from sfepy.base.ioutils import write_vtk
            ## cc = nla.norm( vec_nu )
            ## nun = nu / cc
            ## out = {'v' : Struct( mode = 'vertex', data = nun,
            ##                      ap_name = 'nic', dof_types = (0,1,2) )}
            ## fd = open( 'anim/pert_%03d.pvtk' % (ii+1), 'w' )
            ## write_vtk( fd, domain.mesh, out )
            ## fd.close()
            ## print ii

            val = eval_equations(self.ofg_equations,
                                 self.ofg_variables,
                                 term_mode=1,
                                 preserve_caches=True)

            sa.append(val)

        vec_sa = nm.array(sa, nm.float64)
        return vec_sa
Esempio n. 2
0
    def sensitivity(self, dp_var_data, state_ap, select=None):
        """
        Sensitivity of objective function evaluation for given direct
        and adjoint problem states.
        """
        apb = self.apb

        var_data = state_ap.get_parts()
        var_data.update(dp_var_data)

        self.ofg_equations.set_data(var_data, ignore_unknown=True)

        dim = self.sp_boxes.dim
        n_mesh_nod = apb.domain.shape.n_nod

        if select is None:
            idsgs = nm.arange( self.dsg_vars.n_dsg, dtype = nm.int32 )
        else:
            idsgs = select

        sa = []

        pbar = MyBar('sensitivity:')
        pbar.init(len(idsgs))

        shape = (n_mesh_nod, dim)
        for ii, nu in enumerate(self.generate_mesh_velocity(shape, idsgs)):
            pbar.update(ii)
            self.ofg_variables['Nu'].set_data(nu.ravel())

            ## from sfepy.base.ioutils import write_vtk
            ## cc = nla.norm( vec_nu )
            ## nun = nu / cc
            ## out = {'v' : Struct( mode = 'vertex', data = nun,
            ##                      ap_name = 'nic', dof_types = (0,1,2) )}
            ## fd = open( 'anim/pert_%03d.pvtk' % (ii+1), 'w' )
            ## write_vtk( fd, domain.mesh, out )
            ## fd.close()
            ## print ii

            val = eval_equations(self.ofg_equations, self.ofg_variables,
                                 term_mode=1, preserve_caches=True)

            sa.append( val )

        vec_sa = nm.array( sa, nm.float64 )
        return vec_sa
Esempio n. 3
0
def gen_cylinder_mesh(dims,
                      shape,
                      centre,
                      axis='x',
                      force_hollow=False,
                      is_open=False,
                      open_angle=0.0,
                      non_uniform=False,
                      name='cylinder',
                      verbose=True):
    """
    Generate a cylindrical mesh along an axis. Its cross-section can be
    ellipsoidal.

    Parameters
    ----------
    dims : array of 5 floats
        Dimensions of the cylinder: inner surface semi-axes a1, b1, outer
        surface semi-axes a2, b2, length.
    shape : array of 3 ints
        Shape (counts of nodes in radial, circumferential and longitudinal
        directions) of the cylinder mesh.
    centre : array of 3 floats
        Centre of the cylinder.
    axis: one of 'x', 'y', 'z'
        The axis of the cylinder.
    force_hollow : boolean
        Force hollow mesh even if inner radii a1 = b1 = 0.
    is_open : boolean
        Generate an open cylinder segment.
    open_angle : float
        Opening angle in radians.
    non_uniform : boolean
        If True, space the mesh nodes in radial direction so that the element
        volumes are (approximately) the same, making thus the elements towards
        the outer surface thinner.
    name : string
        Mesh name.
    verbose : bool
        If True, show progress of the mesh generation.

    Returns
    -------
    mesh : Mesh instance
    """
    dims = nm.asarray(dims, dtype=nm.float64)
    shape = nm.asarray(shape, dtype=nm.int32)
    centre = nm.asarray(centre, dtype=nm.float64)

    a1, b1, a2, b2, length = dims
    nr, nfi, nl = shape
    origin = centre - nm.array([0.5 * length, 0.0, 0.0])

    dfi = 2.0 * (nm.pi - open_angle) / nfi
    if is_open:
        nnfi = nfi + 1
    else:
        nnfi = nfi

    is_hollow = force_hollow or not (max(abs(a1), abs(b1)) < 1e-15)

    if is_hollow:
        mr = 0
    else:
        mr = (nnfi - 1) * nl

    grid = nm.zeros((nr, nnfi, nl), dtype=nm.int32)

    n_nod = nr * nnfi * nl - mr
    coors = nm.zeros((n_nod, 3), dtype=nm.float64)

    angles = nm.linspace(open_angle, open_angle + (nfi) * dfi, nfi + 1)
    xs = nm.linspace(0.0, length, nl)
    if non_uniform:
        ras = nm.zeros((nr, ), dtype=nm.float64)
        rbs = nm.zeros_like(ras)
        advol = (a2**2 - a1**2) / (nr - 1)
        bdvol = (b2**2 - b1**2) / (nr - 1)
        ras[0], rbs[0] = a1, b1
        for ii in range(1, nr):
            ras[ii] = nm.sqrt(advol + ras[ii - 1]**2)
            rbs[ii] = nm.sqrt(bdvol + rbs[ii - 1]**2)
    else:
        ras = nm.linspace(a1, a2, nr)
        rbs = nm.linspace(b1, b2, nr)

    # This is 3D only...
    bar = MyBar("       nodes:", verbose=verbose)
    bar.init(n_nod)
    ii = 0
    for ix in range(nr):
        a, b = ras[ix], rbs[ix]
        for iy, fi in enumerate(angles[:nnfi]):
            for iz, x in enumerate(xs):
                grid[ix, iy, iz] = ii
                coors[ii] = origin + [x, a * nm.cos(fi), b * nm.sin(fi)]
                if not (ii % 100):
                    bar.update(ii)
                ii += 1

                if not is_hollow and (ix == 0):
                    if iy > 0:
                        grid[ix, iy, iz] = grid[ix, 0, iz]
                        ii -= 1
    assert_(ii == n_nod)

    n_el = (nr - 1) * nnfi * (nl - 1)
    conn = nm.zeros((n_el, 8), dtype=nm.int32)

    bar = MyBar("       elements:", verbose=verbose)
    bar.init(n_el)
    ii = 0
    for (ix, iy, iz) in cycle([nr - 1, nnfi, nl - 1]):
        if iy < (nnfi - 1):
            conn[ii, :] = [
                grid[ix, iy, iz], grid[ix + 1, iy, iz], grid[ix + 1, iy + 1,
                                                             iz],
                grid[ix, iy + 1, iz], grid[ix, iy, iz + 1], grid[ix + 1, iy,
                                                                 iz + 1],
                grid[ix + 1, iy + 1, iz + 1], grid[ix, iy + 1, iz + 1]
            ]
            ii += 1
        elif not is_open:
            conn[ii, :] = [
                grid[ix, iy, iz], grid[ix + 1, iy, iz], grid[ix + 1, 0, iz],
                grid[ix, 0, iz], grid[ix, iy, iz + 1],
                grid[ix + 1, iy, iz + 1], grid[ix + 1, 0, iz + 1], grid[ix, 0,
                                                                        iz + 1]
            ]
            ii += 1

        if not (ii % 100):
            bar.update(ii)

    mat_id = nm.zeros((n_el, ), dtype=nm.int32)
    desc = '3_8'

    assert_(n_nod == (conn.max() + 1))

    if axis == 'z':
        coors = coors[:, [1, 2, 0]]
    elif axis == 'y':
        coors = coors[:, [2, 0, 1]]

    mesh = Mesh.from_data(name, coors, None, [conn], [mat_id], [desc])
    return mesh
Esempio n. 4
0
def gen_tiled_mesh(mesh, grid=None, scale=1.0, eps=1e-6, ret_ndmap=False):
    """
    Generate a new mesh by repeating a given periodic element
    along each axis.

    Parameters
    ----------
    mesh : Mesh instance
        The input periodic FE mesh.
    grid : array
        Number of repetition along each axis.
    scale : float, optional
        Scaling factor.
    eps : float, optional
        Tolerance for boundary detection.
    ret_ndmap : bool, optional
        If True, return global node map.

    Returns
    -------
    mesh_out : Mesh instance
        FE mesh.
    ndmap : array
        Maps: actual node id --> node id in the reference cell.
    """
    bbox = mesh.get_bounding_box()

    if grid is None:
        iscale = max(int(1.0 / scale), 1)
        grid = [iscale] * mesh.dim

    conns = mesh.conns[0]
    for ii in mesh.conns[1:]:
        conns = nm.vstack((conns, ii))
    mat_ids = mesh.mat_ids[0]
    for ii in mesh.mat_ids[1:]:
        mat_ids = nm.hstack((mat_ids, ii))

    coors = mesh.coors
    ngrps = mesh.ngroups
    nrep = nm.prod(grid)
    ndmap = None

    bar = MyBar("       repeating:")
    bar.init(nrep)
    nblk = 1
    for ii, gr in enumerate(grid):
        if ret_ndmap:
            (conns, coors, ngrps, ndmap0) = tiled_mesh1d(conns,
                                                         coors,
                                                         ngrps,
                                                         ii,
                                                         gr,
                                                         bbox.transpose()[ii],
                                                         eps=eps,
                                                         mybar=(bar, nblk),
                                                         ndmap=ndmap)
            ndmap = ndmap0

        else:
            conns, coors, ngrps = tiled_mesh1d(conns,
                                               coors,
                                               ngrps,
                                               ii,
                                               gr,
                                               bbox.transpose()[ii],
                                               eps=eps,
                                               mybar=(bar, nblk))
        nblk *= gr

    bar.update(nblk)

    mat_ids = nm.tile(mat_ids, (nrep, ))
    mesh_out = Mesh.from_data('tiled mesh', coors * scale, ngrps, [conns],
                              [mat_ids], [mesh.descs[0]])

    if ret_ndmap:
        return mesh_out, ndmap
    else:
        return mesh_out
Esempio n. 5
0
def gen_block_mesh(dims, shape, centre, mat_id=0, name='block', verbose=True):
    """
    Generate a 2D or 3D block mesh. The dimension is determined by the
    lenght of the shape argument.

    Parameters
    ----------
    dims : array of 2 or 3 floats
        Dimensions of the block.
    shape : array of 2 or 3 ints
        Shape (counts of nodes in x, y, z) of the block mesh.
    centre : array of 2 or 3 floats
        Centre of the block.
    mat_id : int, optional
        The material id of all elements.
    name : string
        Mesh name.
    verbose : bool
        If True, show progress of the mesh generation.

    Returns
    -------
    mesh : Mesh instance
    """
    dims = nm.asarray(dims, dtype=nm.float64)
    shape = nm.asarray(shape, dtype=nm.int32)
    centre = nm.asarray(centre, dtype=nm.float64)

    dim = shape.shape[0]

    centre = centre[:dim]
    dims = dims[:dim]

    x0 = centre - 0.5 * dims
    dd = dims / (shape - 1)

    grid = nm.zeros(shape, dtype=nm.int32)
    n_nod = nm.prod(shape)
    coors = nm.zeros((n_nod, dim), dtype=nm.float64)

    bar = MyBar("       nodes:", verbose=verbose)
    bar.init(n_nod)
    for ii, ic in enumerate(cycle(shape)):
        grid[tuple(ic)] = ii
        coors[ii] = x0 + ic * dd
        if not (ii % 100):
            bar.update(ii)
    bar.update(ii + 1)

    n_el = nm.prod(shape - 1)
    mat_ids = nm.empty((n_el, ), dtype=nm.int32)
    mat_ids.fill(mat_id)

    if (dim == 2):
        conn = nm.zeros((n_el, 4), dtype=nm.int32)
        bar = MyBar("       elements:", verbose=verbose)
        bar.init(n_el)
        for ii, (ix, iy) in enumerate(cycle(shape - 1)):
            conn[ii, :] = [
                grid[ix, iy], grid[ix + 1, iy], grid[ix + 1, iy + 1],
                grid[ix, iy + 1]
            ]
            if not (ii % 100):
                bar.update(ii)
        bar.update(ii + 1)
        desc = '2_4'

    else:
        conn = nm.zeros((n_el, 8), dtype=nm.int32)
        bar = MyBar("       elements:", verbose=verbose)
        bar.init(n_el)
        for ii, (ix, iy, iz) in enumerate(cycle(shape - 1)):
            conn[ii, :] = [
                grid[ix, iy, iz], grid[ix + 1, iy, iz], grid[ix + 1, iy + 1,
                                                             iz],
                grid[ix, iy + 1, iz], grid[ix, iy, iz + 1], grid[ix + 1, iy,
                                                                 iz + 1],
                grid[ix + 1, iy + 1, iz + 1], grid[ix, iy + 1, iz + 1]
            ]
            if not (ii % 100):
                bar.update(ii)
        bar.update(ii + 1)
        desc = '3_8'

    mesh = Mesh.from_data(name, coors, None, [conn], [mat_ids], [desc])
    return mesh
Esempio n. 6
0
def gen_block_mesh(dims, shape, centre, name='block'):
    """
    Generate a 2D or 3D block mesh. The dimension is determined by the
    lenght of the shape argument.

    Parameters
    ----------
    dims : array of 2 or 3 floats
        Dimensions of the block.
    shape : array of 2 or 3 ints
        Shape (counts of nodes in x, y, z) of the block mesh.
    centre : array of 2 or 3 floats
        Centre of the block.

    name : string
        Mesh name.

    Returns
    -------
    mesh : Mesh instance
    """
    dims = nm.asarray(dims, dtype=nm.float64)
    shape = nm.asarray(shape, dtype=nm.int32)
    centre = nm.asarray(centre, dtype=nm.float64)

    dim = shape.shape[0]

    centre = centre[:dim]
    dims = dims[:dim]

    x0 = centre - 0.5 * dims
    dd = dims / (shape - 1)

    grid = nm.zeros(shape, dtype = nm.int32)
    n_nod = nm.prod(shape)
    coors = nm.zeros((n_nod, dim), dtype = nm.float64)

    bar = MyBar("       nodes:")
    bar.init(n_nod)
    for ii, ic in enumerate(cycle(shape)):
        grid[tuple(ic)] = ii
        coors[ii] = x0 + ic * dd
        if not (ii % 100):
            bar.update(ii)
    bar.update(ii + 1)

    n_el = nm.prod(shape - 1)
    mat_id = nm.zeros((n_el,), dtype = nm.int32)

    if (dim == 2):
        conn = nm.zeros((n_el, 4), dtype = nm.int32)
        bar = MyBar("       elements:")
        bar.init(n_el)
        for ii, (ix, iy) in enumerate(cycle(shape - 1)):
            conn[ii,:] = [grid[ix  ,iy], grid[ix+1,iy  ],
                          grid[ix+1,iy+1], grid[ix  ,iy+1]]
            if not (ii % 100):
                bar.update(ii)
        bar.update(ii + 1)
        desc = '2_4'

    else:
        conn = nm.zeros((n_el, 8), dtype = nm.int32)
        bar = MyBar("       elements:")
        bar.init(n_el)
        for ii, (ix, iy, iz) in enumerate(cycle(shape - 1)):
            conn[ii,:] = [grid[ix  ,iy  ,iz  ], grid[ix+1,iy  ,iz  ],
                          grid[ix+1,iy+1,iz  ], grid[ix  ,iy+1,iz  ],
                          grid[ix  ,iy  ,iz+1], grid[ix+1,iy  ,iz+1],
                          grid[ix+1,iy+1,iz+1], grid[ix  ,iy+1,iz+1]]
            if not (ii % 100):
                bar.update(ii)
        bar.update(ii + 1)
        desc = '3_8'

    mesh = Mesh.from_data(name, coors, None, [conn], [mat_id], [desc])
    return mesh
Esempio n. 7
0
def gen_cylinder_mesh(dims, shape, centre, axis='x', force_hollow=False,
                      is_open=False, open_angle=0.0, non_uniform=False,
                      name='cylinder'):
    """
    Generate a cylindrical mesh along an axis. Its cross-section can be
    ellipsoidal.

    Parameters
    ----------
    axis: one of 'x', 'y', 'z'
        The axis of the cylinder.
    dims : array of 5 floats
        Dimensions of the cylinder: inner surface semi-axes a1, b1, outer
        surface semi-axes a2, b2, length.
    shape : array of 3 ints
        Shape (counts of nodes in radial, circumferential and longitudinal
        directions) of the cylinder mesh.
    centre : array of 3 floats
        Centre of the cylinder.

    force_hollow : boolean
        Force hollow mesh even if inner radii a1 = b1 = 0.

    is_open : boolean
        Generate an open cylinder segment.
    open_angle : float
        Opening angle in radians.

    non_uniform : boolean
        If True, space the mesh nodes in radial direction so that the element
        volumes are (approximately) the same, making thus the elements towards
        the outer surface thinner.

    name : string
        Mesh name.

    Returns
    -------
    mesh : Mesh instance
    """
    dims = nm.asarray(dims, dtype=nm.float64)
    shape = nm.asarray(shape, dtype=nm.int32)
    centre = nm.asarray(centre, dtype=nm.float64)

    a1, b1, a2, b2, length = dims
    nr, nfi, nl = shape
    origin = centre - nm.array([0.5 * length, 0.0, 0.0])

    dfi = 2.0 * (nm.pi - open_angle) / nfi
    if is_open:
        nnfi = nfi + 1
    else:
        nnfi = nfi

    is_hollow = force_hollow or not (max(abs(a1), abs(b1)) < 1e-15)

    if is_hollow:
        mr = 0
    else:
        mr = (nnfi - 1) * nl

    grid = nm.zeros((nr, nnfi, nl), dtype=nm.int32)

    n_nod = nr * nnfi * nl - mr
    coors = nm.zeros((n_nod, 3), dtype=nm.float64)

    angles = nm.linspace(open_angle, open_angle+(nfi)*dfi, nfi+1)
    xs = nm.linspace(0.0, length, nl)
    if non_uniform:
        ras = nm.zeros((nr,), dtype=nm.float64)
        rbs = nm.zeros_like(ras)
        advol = (a2**2 - a1**2) / (nr - 1)
        bdvol = (b2**2 - b1**2) / (nr - 1)
        ras[0], rbs[0] = a1, b1
        for ii in range(1, nr):
            ras[ii] = nm.sqrt(advol + ras[ii-1]**2)
            rbs[ii] = nm.sqrt(bdvol + rbs[ii-1]**2)
    else:
        ras = nm.linspace(a1, a2, nr)
        rbs = nm.linspace(b1, b2, nr)

    # This is 3D only...
    bar = MyBar("       nodes:")
    bar.init(n_nod)
    ii = 0
    for ix in range(nr):
        a, b = ras[ix], rbs[ix]
        for iy, fi in enumerate(angles[:nnfi]):
            for iz, x in enumerate(xs):
                grid[ix,iy,iz] = ii
                coors[ii] = origin + [x, a * nm.cos(fi), b * nm.sin(fi)]
                if not (ii % 100):
                    bar.update(ii)
                ii += 1

                if not is_hollow and (ix == 0):
                    if iy > 0:
                        grid[ix,iy,iz] = grid[ix,0,iz]
                        ii -= 1
    print
    assert_(ii == n_nod)

    n_el = (nr - 1) * nnfi * (nl - 1)
    conn = nm.zeros((n_el, 8), dtype=nm.int32)

    bar = MyBar("       elements:")
    bar.init(n_el)
    ii = 0
    for (ix, iy, iz) in cycle([nr-1, nnfi, nl-1]):
        if iy < (nnfi - 1):
            conn[ii,:] = [grid[ix  ,iy  ,iz  ], grid[ix+1,iy  ,iz  ],
                          grid[ix+1,iy+1,iz  ], grid[ix  ,iy+1,iz  ],
                          grid[ix  ,iy  ,iz+1], grid[ix+1,iy  ,iz+1],
                          grid[ix+1,iy+1,iz+1], grid[ix  ,iy+1,iz+1]]
            ii += 1
        elif not is_open:
            conn[ii,:] = [grid[ix  ,iy  ,iz  ], grid[ix+1,iy  ,iz  ],
                          grid[ix+1,0,iz  ], grid[ix  ,0,iz  ],
                          grid[ix  ,iy  ,iz+1], grid[ix+1,iy  ,iz+1],
                          grid[ix+1,0,iz+1], grid[ix  ,0,iz+1]]
            ii += 1

        if not (ii % 100):
            bar.update(ii)
    print
    mat_id = nm.zeros((n_el,), dtype = nm.int32)
    desc = '3_8'

    assert_(n_nod == (conn.max() + 1))

    if axis == 'z':
        coors = coors[:,[1,2,0]]
    elif axis == 'y':
        coors = coors[:,[2,0,1]]

    mesh = Mesh.from_data(name, coors, None, [conn], [mat_id], [desc])
    return mesh
Esempio n. 8
0
def gen_tiled_mesh(mesh, grid=None, scale=1.0, eps=1e-6, ret_ndmap=False):
    """
    Generate a new mesh by repeating a given periodic element
    along each axis.

    Parameters
    ----------
    mesh : Mesh instance
        The input periodic FE mesh.
    grid : array
        Number of repetition along each axis.
    scale : float, optional
        Scaling factor.
    eps : float, optional
        Tolerance for boundary detection.
    ret_ndmap : bool, optional
        If True, return global node map.

    Returns
    -------
    mesh_out : Mesh instance
        FE mesh.
    ndmap : array
        Maps: actual node id --> node id in the reference cell.
    """
    bbox = mesh.get_bounding_box()

    if grid is None:
        iscale = max(int(1.0 / scale), 1)
        grid = [iscale] * mesh.dim

    conns = mesh.conns[0]
    for ii in mesh.conns[1:]:
        conns = nm.vstack((conns, ii))
    mat_ids = mesh.mat_ids[0]
    for ii in mesh.mat_ids[1:]:
        mat_ids = nm.hstack((mat_ids, ii))

    coors = mesh.coors
    ngrps = mesh.ngroups
    nrep = nm.prod(grid)
    ndmap = None

    bar = MyBar("       repeating:")
    bar.init(nrep)
    nblk = 1
    for ii, gr in enumerate(grid):
        if ret_ndmap:
            (conns, coors,
             ngrps, ndmap0) = tiled_mesh1d(conns, coors, ngrps,
                                           ii, gr, bbox.transpose()[ii],
                                           eps=eps, mybar=(bar, nblk),
                                           ndmap=ndmap)
            ndmap = ndmap0

        else:
            conns, coors, ngrps = tiled_mesh1d(conns, coors, ngrps,
                                               ii, gr, bbox.transpose()[ii],
                                               eps=eps, mybar=(bar, nblk))
        nblk *= gr

    bar.update(nblk)

    mat_ids = nm.tile(mat_ids, (nrep,))
    mesh_out = Mesh.from_data('tiled mesh', coors * scale, ngrps,
                              [conns], [mat_ids], [mesh.descs[0]])

    if ret_ndmap:
        return mesh_out, ndmap
    else:
        return mesh_out
Esempio n. 9
0
def main():
    parser = OptionParser(usage=usage, version="%prog")
    parser.add_option(
        "-o", "", metavar="filename", action="store", dest="output_filename", default="out.vtk", help=help["filename"]
    )
    parser.add_option(
        "-d", "--dims", metavar="dims", action="store", dest="dims", default="[1.0, 1.0, 1.0]", help=help["dims"]
    )
    parser.add_option(
        "-s", "--shape", metavar="shape", action="store", dest="shape", default="[11, 11, 11]", help=help["shape"]
    )
    parser.add_option(
        "-c",
        "--centre",
        metavar="centre",
        action="store",
        dest="centre",
        default="[0.0, 0.0, 0.0]",
        help=help["centre"],
    )
    (options, args) = parser.parse_args()

    dims = eval("nm.array( %s, dtype = nm.float64 )" % options.dims)
    shape = eval("nm.array( %s, dtype = nm.int32 )" % options.shape)
    centre = eval("nm.array( %s, dtype = nm.float64 )" % options.centre)

    print dims
    print shape
    print centre

    dim = shape.shape[0]

    x0 = centre - 0.5 * dims
    dd = dims / (shape - 1)

    grid = nm.zeros(shape, dtype=nm.float64)
    n_nod = nm.prod(shape)
    coors = nm.zeros((n_nod, dim + 1), dtype=nm.float64)

    # This is 3D only...
    bar = MyBar("       nodes:")
    bar.init(n_nod)
    for ii, ic in enumerate(cycle(shape)):
        ix, iy, iz = ic
        grid[ix, iy, iz] = ii
        coors[ii, :-1] = x0 + ic * dd
        if not (ii % 100):
            bar.update(ii)
    print
    n_el = nm.prod(shape - 1)
    conn = nm.zeros((n_el, 8), dtype=nm.int32)
    bar = MyBar("       elements:")
    bar.init(n_el)
    for ii, (ix, iy, iz) in enumerate(cycle(shape - 1)):
        conn[ii, :] = [
            grid[ix, iy, iz],
            grid[ix + 1, iy, iz],
            grid[ix + 1, iy + 1, iz],
            grid[ix, iy + 1, iz],
            grid[ix, iy, iz + 1],
            grid[ix + 1, iy, iz + 1],
            grid[ix + 1, iy + 1, iz + 1],
            grid[ix, iy + 1, iz + 1],
        ]
        if not (ii % 100):
            bar.update(ii)
    print
    mat_id = nm.zeros((n_el,), dtype=nm.int32)
    desc = "3_8"

    mesh = Mesh.from_data(options.output_filename, coors, [conn], [mat_id], [desc])
    mesh.write(options.output_filename, io="auto")