def main():
    parser = ArgumentParser(description=__doc__,
                            formatter_class=RawDescriptionHelpFormatter)
    parser.add_argument('--version', action='version', version='%(prog)s')
    parser.add_argument('-d',
                        '--dims',
                        metavar='dims',
                        action='store',
                        dest='dims',
                        default='[1.0, 1.0]',
                        help=helps['dims'])
    parser.add_argument('-c',
                        '--centre',
                        metavar='centre',
                        action='store',
                        dest='centre',
                        default='[0.0, 0.0]',
                        help=helps['centre'])
    parser.add_argument('-s',
                        '--shape',
                        metavar='shape',
                        action='store',
                        dest='shape',
                        default='[11, 11]',
                        help=helps['shape'])
    parser.add_argument('--show',
                        action="store_true",
                        dest='show',
                        default=False,
                        help=helps['show'])
    options = parser.parse_args()

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

    output('dimensions:', dims)
    output('centre:    ', centre)
    output('shape:     ', shape)

    mesh = gen_block_mesh(dims, shape, centre, name='block-fem')
    fe_domain = FEDomain('domain', mesh)

    pb, state = run(fe_domain, 1)
    pb.save_state('laplace_shifted_periodic.vtk', state)

    if options.show:
        from sfepy.postprocess.viewer import Viewer
        from sfepy.postprocess.domain_specific import DomainSpecificPlot

        view = Viewer('laplace_shifted_periodic.vtk')
        view(rel_scaling=1,
             domain_specific={
                 'u': DomainSpecificPlot('plot_warp_scalar', ['rel_scaling=1'])
             },
             is_scalar_bar=True,
             is_wireframe=True,
             opacity=0.3)
예제 #2
0
파일: postproc.py 프로젝트: zitkat/sfepy
    def __call__(self, parser, namespace, value, option_string=None):
        if value is not None:
            print(value)
            out = {}
            confs = value.split(':')
            for conf in confs:
                aux = conf.split(',')
                var_name, fun_name = aux[:2]
                args = aux[2:]

                out[var_name] = DomainSpecificPlot(fun_name, args)
            setattr(namespace, self.dest, out)
예제 #3
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def parse_domain_specific(option, opt, value, parser):
    if value is not None:
        print value
        out = {}
        confs = value.split(':')
        for conf in confs:
            aux = conf.split(',')
            var_name, fun_name = aux[:2]
            args = aux[2:]

            out[var_name] = DomainSpecificPlot(fun_name, args)

        setattr(parser.values, option.dest, out)
def main():
    parser = ArgumentParser(description=__doc__.rstrip(),
                            formatter_class=RawDescriptionHelpFormatter)
    parser.add_argument('output_dir', help=helps['output_dir'])
    parser.add_argument('-d', '--dims', metavar='l,w,t',
                        action='store', dest='dims',
                        default='0.2,0.01,0.001', help=helps['dims'])
    parser.add_argument('-n', '--nx', metavar='start,stop,step',
                        action='store', dest='nx',
                        default='2,103,10', help=helps['nx'])
    parser.add_argument('-t', '--transform', choices=['none', 'bend', 'twist'],
                        action='store', dest='transform',
                        default='none', help=helps['transform'])
    parser.add_argument('--young', metavar='float', type=float,
                        action='store', dest='young',
                        default=210e9, help=helps['young'])
    parser.add_argument('--poisson', metavar='float', type=float,
                        action='store', dest='poisson',
                        default=0.3, help=helps['poisson'])
    parser.add_argument('--force', metavar='float', type=float,
                        action='store', dest='force',
                        default=-1.0, help=helps['force'])
    parser.add_argument('-p', '--plot',
                        action="store_true", dest='plot',
                        default=False, help=helps['plot'])
    parser.add_argument('--u-scaling', metavar='float', type=float,
                        action='store', dest='scaling',
                        default=1.0, help=helps['scaling'])
    parser.add_argument('-s', '--show',
                        action="store_true", dest='show',
                        default=False, help=helps['show'])
    parser.add_argument('--silent',
                        action='store_true', dest='silent',
                        default=False, help=helps['silent'])
    options = parser.parse_args()

    dims = nm.array([float(ii) for ii in options.dims.split(',')],
                    dtype=nm.float64)
    nxs = tuple([int(ii) for ii in options.nx.split(',')])
    young = options.young
    poisson = options.poisson
    force = options.force

    output_dir = options.output_dir

    odir = lambda filename: os.path.join(output_dir, filename)

    filename = odir('output_log.txt')
    ensure_path(filename)
    output.set_output(filename=filename, combined=options.silent == False)

    output('output directory:', output_dir)
    output('using values:')
    output("  dimensions:", dims)
    output("  nx range:", nxs)
    output("  Young's modulus:", options.young)
    output("  Poisson's ratio:", options.poisson)
    output('  force:', options.force)
    output('  transform:', options.transform)

    if options.transform == 'none':
        options.transform = None

    u_exact = get_analytical_displacement(dims, young, force,
                                          transform=options.transform)

    if options.transform is None:
        ilog = 2
        labels = ['u_3']

    elif options.transform == 'bend':
        ilog = 0
        labels = ['u_1']

    elif options.transform == 'twist':
        ilog = [0, 1, 2]
        labels = ['u_1', 'u_2', 'u_3']

    label = ', '.join(labels)

    log = []
    for nx in range(*nxs):
        shape = (nx, 2)

        pb, state, u, gamma2 = solve_problem(shape, dims, young, poisson, force,
                                             transform=options.transform)

        dofs = u.get_state_in_region(gamma2)
        output('DOFs along the loaded edge:')
        output('\n%s' % dofs)

        log.append([nx - 1] + nm.array(dofs[0, ilog], ndmin=1).tolist())

    pb.save_state(odir('shell10x_cantilever.vtk'), state)

    log = nm.array(log)

    output('max. %s displacement w.r.t. number of cells:' % label)
    output('\n%s' % log)
    output('analytical value:', u_exact)

    if options.plot:
        import matplotlib.pyplot as plt

        plt.rcParams.update({
            'lines.linewidth' : 3,
            'font.size' : 16,
        })

        fig, ax1 = plt.subplots()
        fig.suptitle('max. $%s$ displacement' % label)

        for ic in range(log.shape[1] - 1):
            ax1.plot(log[:, 0], log[:, ic + 1], label=r'$%s$' % labels[ic])
        ax1.set_xlabel('# of cells')
        ax1.set_ylabel(r'$%s$' % label)
        ax1.grid(which='both')

        lines1, labels1 = ax1.get_legend_handles_labels()

        if u_exact is not None:
            ax1.hlines(u_exact, log[0, 0], log[-1, 0],
                       'r', 'dotted', label=r'$%s^{analytical}$' % label)

            ax2 = ax1.twinx()
            # Assume single log column.
            ax2.semilogy(log[:, 0], nm.abs(log[:, 1] - u_exact), 'g',
                         label=r'$|%s - %s^{analytical}|$' % (label, label))
            ax2.set_ylabel(r'$|%s - %s^{analytical}|$' % (label, label))

            lines2, labels2 = ax2.get_legend_handles_labels()

        else:
            lines2, labels2 = [], []

        ax1.legend(lines1 + lines2, labels1 + labels2, loc='best')

        plt.tight_layout()
        ax1.set_xlim([log[0, 0] - 2, log[-1, 0] + 2])

        suffix = {None: 'straight',
                  'bend' : 'bent', 'twist' : 'twisted'}[options.transform]
        fig.savefig(odir('shell10x_cantilever_convergence_%s.png' % suffix))

        plt.show()

    if options.show:
        from sfepy.postprocess.viewer import Viewer
        from sfepy.postprocess.domain_specific import DomainSpecificPlot

        ds = {'u_disp' :
                  DomainSpecificPlot('plot_displacements',
                                     ['rel_scaling=%f' % options.scaling])}
        view = Viewer(odir('shell10x_cantilever.vtk'))
        view(domain_specific=ds, is_scalar_bar=True, is_wireframe=True,
             opacity={'wireframe' : 0.5})
예제 #5
0
파일: gen_gallery.py 프로젝트: mfkiwl/sfepy
    'vibro_acoustic3d_mid.py',
    'linear_elastic_mM.py',
    'time_poisson_explicit.py',
    '__init__.py',
]

omit_dirs = [
    re.compile('.*output.*/').match,
]

custom = {
    'diffusion/sinbc.py' : {
        '_t' : {
            'is_wireframe' : True,
            'domain_specific' : {
                't' : DomainSpecificPlot('plot_warp_scalar',
                                         ['rel_scaling=1']),
            },
            'view' : (-160, 33, 4, [0.5, 1.22, 0.05]),
            'roll' : 68,
            'opacity' : {'wireframe' : 0.3},
        },
        '_grad' : {
            'opacity' : {'surface' : 0.3},
            'view' : (-160, 33, 4, [0.5, 1.22, 0.05]),
            'roll' : 68,
        },
    },
    'acoustics/acoustics3d.py' : {
        '_p_1' : {
            'view' : (-53, 120, 0.225, [0.021, 0.018, 0.066]),
            'roll' : -177,
예제 #6
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         'roll': -120,
     },
     '_w': {
         'view': (0.0, 0.0, 0.86, [0.0, 0.0, 0.1]),
         'roll': 0,
     },
     '_g0': {
         'view': (0.0, 0.0, 0.86, [0.0, 0.0, 0.1]),
         'roll': 0,
     },
 },
 'diffusion/laplace_1d.py': {
     '': {
         'is_wireframe': True,
         'domain_specific': {
             't': DomainSpecificPlot('plot_warp_scalar', ['rel_scaling=1']),
         },
         'view': (-90, 90, 1.5, [0, 0, 0]),
         'roll': 0,
         'opacity': {
             'wireframe': 0.3
         },
     },
 },
 'diffusion/laplace_coupling_lcbcs.py': {
     '': {
         'is_wireframe': True,
         'domain_specific': {
             'u1': DomainSpecificPlot('plot_warp_scalar',
                                      ['rel_scaling=1']),
             'u2': DomainSpecificPlot('plot_warp_scalar',
예제 #7
0
파일: gen_gallery.py 프로젝트: sdurve/sfepy
omits = [
    'linear_elastic_mM.py',
    'time_poisson_explicit.py',
    '__init__.py',
]

omit_dirs = [
    re.compile('.*output.*/').match,
]

custom = {
    'diffusion/sinbc.py' : {
        '_t' : {
            'is_wireframe' : True,
            'domain_specific' : {
                't' : DomainSpecificPlot('plot_warp_scalar',
                                         ['rel_scaling=1']),
            },
            'view' : (-160, 33, 4, [0.5, 1.22, 0.05]),
            'roll' : 68,
            'opacity' : {'wireframe' : 0.3},
        },
        '_grad' : {
            'opacity' : {'surface' : 0.3},
            'view' : (-160, 33, 4, [0.5, 1.22, 0.05]),
            'roll' : 68,
        },
    },
}

def _omit(filename):
    omit = False
def main():
    parser = ArgumentParser(description=__doc__,
                            formatter_class=RawDescriptionHelpFormatter)
    parser.add_argument('--version', action='version', version='%(prog)s')
    parser.add_argument('-d',
                        '--dims',
                        metavar='dims',
                        action='store',
                        dest='dims',
                        default='[1.0, 1.0]',
                        help=helps['dims'])
    parser.add_argument('-c',
                        '--centre',
                        metavar='centre',
                        action='store',
                        dest='centre',
                        default='[0.0, 0.0]',
                        help=helps['centre'])
    parser.add_argument('-s',
                        '--shape',
                        metavar='shape',
                        action='store',
                        dest='shape',
                        default='[11, 11]',
                        help=helps['shape'])
    parser.add_argument('-b',
                        '--bc-kind',
                        metavar='kind',
                        action='store',
                        dest='bc_kind',
                        choices=['free', 'cantilever', 'fixed'],
                        default='free',
                        help=helps['bc_kind'])
    parser.add_argument('-a',
                        '--axis',
                        metavar='0, ..., dim, or -1',
                        type=int,
                        action='store',
                        dest='axis',
                        default=-1,
                        help=helps['axis'])
    parser.add_argument('--young',
                        metavar='float',
                        type=float,
                        action='store',
                        dest='young',
                        default=200e+9,
                        help=helps['young'])
    parser.add_argument('--poisson',
                        metavar='float',
                        type=float,
                        action='store',
                        dest='poisson',
                        default=0.3,
                        help=helps['poisson'])
    parser.add_argument('--density',
                        metavar='float',
                        type=float,
                        action='store',
                        dest='density',
                        default=7800.0,
                        help=helps['density'])
    parser.add_argument('--order',
                        metavar='int',
                        type=int,
                        action='store',
                        dest='order',
                        default=1,
                        help=helps['order'])
    parser.add_argument('-n',
                        '--n-eigs',
                        metavar='int',
                        type=int,
                        action='store',
                        dest='n_eigs',
                        default=6,
                        help=helps['n_eigs'])
    parser.add_argument('-i',
                        '--ignore',
                        metavar='int',
                        type=int,
                        action='store',
                        dest='ignore',
                        default=None,
                        help=helps['ignore'])
    parser.add_argument('--solver', metavar='solver', action='store',
                        dest='solver',
                        default= \
                        "eig.scipy,method:'eigh',tol:1e-5,maxiter:1000",
                        help=helps['solver'])
    parser.add_argument('--show',
                        action="store_true",
                        dest='show',
                        default=False,
                        help=helps['show'])
    #parser.add_argument('filename', nargs='?', default=None)
    #read block.mesh
    #parser.add_argument('filename', nargs='?', default="platehexat200mm.mesh")
    parser.add_argument('filename', nargs='?', default="block_1m.mesh")
    options = parser.parse_args()

    aux = options.solver.split(',')
    kwargs = {}
    for option in aux[1:]:
        key, val = option.split(':')
        kwargs[key.strip()] = eval(val)
    eig_conf = Struct(name='evp', kind=aux[0], **kwargs)

    output('using values:')
    output("  Young's modulus:", options.young)
    output("  Poisson's ratio:", options.poisson)
    output('  density:', options.density)
    output('displacement field approximation order:', options.order)
    output('requested %d eigenvalues' % options.n_eigs)
    output('using eigenvalue problem solver:', eig_conf.kind)
    output.level += 1
    for key, val in six.iteritems(kwargs):
        output('%s: %r' % (key, val))
    output.level -= 1

    assert_((0.0 < options.poisson < 0.5),
            "Poisson's ratio must be in ]0, 0.5[!")
    assert_((0 < options.order),
            'displacement approximation order must be at least 1!')

    filename = options.filename
    if filename is not None:
        mesh = Mesh.from_file(filename)
        dim = mesh.dim
        dims = nm.diff(mesh.get_bounding_box(), axis=0)

    else:
        dims = nm.array(eval(options.dims), dtype=nm.float64)
        dim = len(dims)

        centre = nm.array(eval(options.centre), dtype=nm.float64)[:dim]
        shape = nm.array(eval(options.shape), dtype=nm.int32)[:dim]

        output('dimensions:', dims)
        output('centre:    ', centre)
        output('shape:     ', shape)

        mesh = gen_block_mesh(dims, shape, centre, name='mesh')

    output('axis:      ', options.axis)
    assert_((-dim <= options.axis < dim), 'invalid axis value!')

    eig_solver = Solver.any_from_conf(eig_conf)

    # Build the problem definition.
    domain = FEDomain('domain', mesh)

    bbox = domain.get_mesh_bounding_box()
    min_coor, max_coor = bbox[:, options.axis]
    eps = 1e-8 * (max_coor - min_coor)
    ax = 'xyz'[:dim][options.axis]

    omega = domain.create_region('Omega', 'all')
    """
    bottom = domain.create_region('Bottom',
                                  'vertices in (%s < %.10f)'
                                  % (ax, min_coor + eps),
                                  'facet')

    bottom_top = domain.create_region('BottomTop',
                                      'r.Bottom +v vertices in (%s > %.10f)'
                                      % (ax, max_coor - eps),
                                      'facet')
    """
    #import pdb; pdb.set_trace()
    left = domain.create_region('left', 'vertices in (x < -0.49)', 'facet')

    field = Field.from_args('fu',
                            nm.float64,
                            'vector',
                            omega,
                            approx_order=options.order)

    u = FieldVariable('u', 'unknown', field)
    v = FieldVariable('v', 'test', field, primary_var_name='u')

    mtx_d = stiffness_from_youngpoisson(dim, options.young, options.poisson)

    m = Material('m', D=mtx_d, rho=options.density)

    integral = Integral('i', order=2 * options.order)

    t1 = Term.new('dw_lin_elastic(m.D, v, u)', integral, omega, m=m, v=v, u=u)
    t2 = Term.new('dw_volume_dot(m.rho, v, u)', integral, omega, m=m, v=v, u=u)
    eq1 = Equation('stiffness', t1)
    eq2 = Equation('mass', t2)
    lhs_eqs = Equations([eq1, eq2])

    pb = Problem('modal', equations=lhs_eqs)
    """
    if options.bc_kind == 'free':
        pb.time_update()
        n_rbm = dim * (dim + 1) // 2

    elif options.bc_kind == 'cantilever':
        fixed = EssentialBC('Fixed', bottom, {'u.all' : 0.0})
        pb.time_update(ebcs=Conditions([fixed]))
        n_rbm = 0

    elif options.bc_kind == 'fixed':
        fixed = EssentialBC('Fixed', bottom_top, {'u.all' : 0.0})
        pb.time_update(ebcs=Conditions([fixed]))
        n_rbm = 0

    else:
        raise ValueError('unsupported BC kind! (%s)' % options.bc_kind)

    if options.ignore is not None:
        n_rbm = options.ignore
    """
    fixed = EssentialBC('Fixed', left, {'u.all': 0.0})
    pb.time_update(ebcs=Conditions([fixed]))
    n_rbm = 0

    pb.update_materials()

    # Assemble stiffness and mass matrices.
    mtx_k = eq1.evaluate(mode='weak', dw_mode='matrix', asm_obj=pb.mtx_a)
    mtx_m = mtx_k.copy()
    mtx_m.data[:] = 0.0
    mtx_m = eq2.evaluate(mode='weak', dw_mode='matrix', asm_obj=mtx_m)

    try:
        eigs, svecs = eig_solver(mtx_k,
                                 mtx_m,
                                 options.n_eigs + n_rbm,
                                 eigenvectors=True)

    except sla.ArpackNoConvergence as ee:
        eigs = ee.eigenvalues
        svecs = ee.eigenvectors
        output('only %d eigenvalues converged!' % len(eigs))

    output('%d eigenvalues converged (%d ignored as rigid body modes)' %
           (len(eigs), n_rbm))

    eigs = eigs[n_rbm:]
    svecs = svecs[:, n_rbm:]

    omegas = nm.sqrt(eigs)
    freqs = omegas / (2 * nm.pi)

    output('number |         eigenvalue |  angular frequency '
           '|          frequency')
    for ii, eig in enumerate(eigs):
        output('%6d | %17.12e | %17.12e | %17.12e' %
               (ii + 1, eig, omegas[ii], freqs[ii]))

    # Make full eigenvectors (add DOFs fixed by boundary conditions).
    variables = pb.get_variables()

    vecs = nm.empty((variables.di.ptr[-1], svecs.shape[1]), dtype=nm.float64)
    for ii in range(svecs.shape[1]):
        vecs[:, ii] = variables.make_full_vec(svecs[:, ii])

    # Save the eigenvectors.
    out = {}
    state = pb.create_state()
    for ii in range(eigs.shape[0]):
        state.set_full(vecs[:, ii])
        aux = state.create_output_dict()
        strain = pb.evaluate('ev_cauchy_strain.i.Omega(u)',
                             integrals=Integrals([integral]),
                             mode='el_avg',
                             verbose=False)
        out['u%03d' % ii] = aux.popitem()[1]
        out['strain%03d' % ii] = Struct(mode='cell', data=strain)

    pb.save_state('eigenshapes.vtk', out=out)
    pb.save_regions_as_groups('regions')

    if len(eigs) and options.show:
        # Show the solution. If the approximation order is greater than 1, the
        # extra DOFs are simply thrown away.
        from sfepy.postprocess.viewer import Viewer
        from sfepy.postprocess.domain_specific import DomainSpecificPlot

        scaling = 0.05 * dims.max() / nm.abs(vecs).max()

        ds = {}
        for ii in range(eigs.shape[0]):
            pd = DomainSpecificPlot('plot_displacements', [
                'rel_scaling=%s' % scaling, 'color_kind="tensors"',
                'color_name="strain%03d"' % ii
            ])
            ds['u%03d' % ii] = pd

        view = Viewer('eigenshapes.vtk')
        view(domain_specific=ds,
             only_names=sorted(ds.keys()),
             is_scalar_bar=False,
             is_wireframe=True)
예제 #9
0
def main():
    parser = OptionParser(usage=usage, version='%prog')
    parser.add_option('-d',
                      '--dims',
                      metavar='dims',
                      action='store',
                      dest='dims',
                      default='[1.0, 1.0]',
                      help=helps['dims'])
    parser.add_option('-c',
                      '--centre',
                      metavar='centre',
                      action='store',
                      dest='centre',
                      default='[0.0, 0.0]',
                      help=helps['centre'])
    parser.add_option('-s',
                      '--shape',
                      metavar='shape',
                      action='store',
                      dest='shape',
                      default='[11, 11]',
                      help=helps['shape'])
    parser.add_option('-b',
                      '--bc-kind',
                      metavar='kind',
                      action='store',
                      dest='bc_kind',
                      choices=['free', 'clamped'],
                      default='free',
                      help=helps['bc_kind'])
    parser.add_option('--young',
                      metavar='float',
                      type=float,
                      action='store',
                      dest='young',
                      default=6.80e+10,
                      help=helps['young'])
    parser.add_option('--poisson',
                      metavar='float',
                      type=float,
                      action='store',
                      dest='poisson',
                      default=0.36,
                      help=helps['poisson'])
    parser.add_option('--density',
                      metavar='float',
                      type=float,
                      action='store',
                      dest='density',
                      default=2700.0,
                      help=helps['density'])
    parser.add_option('--order',
                      metavar='int',
                      type=int,
                      action='store',
                      dest='order',
                      default=1,
                      help=helps['order'])
    parser.add_option('-n',
                      '--n-eigs',
                      metavar='int',
                      type=int,
                      action='store',
                      dest='n_eigs',
                      default=6,
                      help=helps['order'])
    parser.add_option('',
                      '--show',
                      action="store_true",
                      dest='show',
                      default=False,
                      help=helps['show'])
    options, args = parser.parse_args()

    assert_((0.0 < options.poisson < 0.5),
            "Poisson's ratio must be in ]0, 0.5[!")
    assert_((0 < options.order),
            'displacement approximation order must be at least 1!')

    dims = nm.array(eval(options.dims), dtype=nm.float64)
    dim = len(dims)
    centre = nm.array(eval(options.centre), dtype=nm.float64)[:dim]
    shape = nm.array(eval(options.shape), dtype=nm.int32)[:dim]

    output('dimensions:', dims)
    output('centre:    ', centre)
    output('shape:     ', shape)
    output('using values:')
    output("  Young's modulus:", options.young)
    output("  Poisson's ratio:", options.poisson)
    output('  density:', options.density)

    # Build the problem definition.
    mesh = gen_block_mesh(dims, shape, centre, name='mesh')
    domain = FEDomain('domain', mesh)

    bbox = domain.get_mesh_bounding_box()
    min_y, max_y = bbox[:, 1]
    eps = 1e-8 * (max_y - min_y)
    omega = domain.create_region('Omega', 'all')
    bottom = domain.create_region('Bottom',
                                  'vertices in (y < %.10f)' % (min_y + eps),
                                  'facet')

    field = Field.from_args('fu',
                            nm.float64,
                            'vector',
                            omega,
                            approx_order=options.order)

    u = FieldVariable('u', 'unknown', field)
    v = FieldVariable('v', 'test', field, primary_var_name='u')

    mtx_d = stiffness_from_youngpoisson(dim, options.young, options.poisson)

    m = Material('m', D=mtx_d, rho=options.density)

    integral = Integral('i', order=2 * options.order)

    t1 = Term.new('dw_lin_elastic(m.D, v, u)', integral, omega, m=m, v=v, u=u)
    t2 = Term.new('dw_volume_dot(m.rho, v, u)', integral, omega, m=m, v=v, u=u)
    eq1 = Equation('stiffness', t1)
    eq2 = Equation('mass', t2)
    lhs_eqs = Equations([eq1, eq2])

    pb = Problem('modal', equations=lhs_eqs)

    if options.bc_kind == 'free':
        pb.time_update()
        n_rbm = dim * (dim + 1) / 2

    else:
        fixed_b = EssentialBC('FixedB', bottom, {'u.all': 0.0})
        pb.time_update(ebcs=Conditions([fixed_b]))
        n_rbm = 0

    pb.update_materials()

    # Assemble stiffness and mass matrices.
    mtx_k = eq1.evaluate(mode='weak', dw_mode='matrix', asm_obj=pb.mtx_a)
    mtx_m = mtx_k.copy()
    mtx_m.data[:] = 0.0
    mtx_m = eq2.evaluate(mode='weak', dw_mode='matrix', asm_obj=mtx_m)

    try:
        eigs, svecs = sla.eigsh(mtx_k,
                                k=options.n_eigs + n_rbm,
                                M=mtx_m,
                                which='SM',
                                tol=1e-5,
                                maxiter=10000)
    except sla.ArpackNoConvergence as ee:
        eigs = ee.eigenvalues
        svecs = ee.eigenvectors
        output('only %d eigenvalues converged!' % len(eigs))

    eigs = eigs[n_rbm:]
    svecs = svecs[:, n_rbm:]

    output('eigenvalues:', eigs)
    output('eigen-frequencies:', nm.sqrt(eigs))

    # Make full eigenvectors (add DOFs fixed by boundary conditions).
    variables = pb.get_variables()

    vecs = nm.empty((variables.di.ptr[-1], svecs.shape[1]), dtype=nm.float64)
    for ii in xrange(svecs.shape[1]):
        vecs[:, ii] = variables.make_full_vec(svecs[:, ii])

    # Save the eigenvectors.
    out = {}
    state = pb.create_state()
    for ii in xrange(eigs.shape[0]):
        state.set_full(vecs[:, ii])
        aux = state.create_output_dict()
        strain = pb.evaluate('ev_cauchy_strain.i.Omega(u)',
                             integrals=Integrals([integral]),
                             mode='el_avg',
                             verbose=False)
        out['u%03d' % ii] = aux.popitem()[1]
        out['strain%03d' % ii] = Struct(mode='cell', data=strain)

    pb.save_state('eigenshapes.vtk', out=out)
    pb.save_regions_as_groups('regions')

    if options.show:
        # Show the solution. If the approximation order is greater than 1, the
        # extra DOFs are simply thrown away.
        from sfepy.postprocess.viewer import Viewer
        from sfepy.postprocess.domain_specific import DomainSpecificPlot

        scaling = 0.05 * dims.max() / nm.abs(vecs).max()

        ds = {}
        for ii in xrange(eigs.shape[0]):
            pd = DomainSpecificPlot('plot_displacements', [
                'rel_scaling=%s' % scaling, 'color_kind="tensors"',
                'color_name="strain%03d"' % ii
            ])
            ds['u%03d' % ii] = pd

        view = Viewer('eigenshapes.vtk')
        view(domain_specific=ds,
             only_names=sorted(ds.keys()),
             is_scalar_bar=False,
             is_wireframe=True)