Error in sage tutorial coding theory - sage

Question

I have just installed sage 6.3 in Ubuntu 14.04 and I have tried the tutorial in coding theory as follow:
MS = MatrixSpace(GF(2),4,7)
G = MS([[1,1,1,0,0,0,0], [1,0,0,1,1,0,0], [0,1,0,1,0,1,0], [1,1,0,1,0,0,1]])
C = LinearCode(G)
In the third evaluation, sage produced error as follow:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_4.py", line 10, in <module>
exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8 -*-\\n" + _support_.preparse_worksheet_cell(base64.b64decode("QyA9IExpbmVhckNvZGUoRyk="),globals())+"\\n"); execfile(os.path.abspath("___code___.py"))
File "", line 1, in <module>
File "/tmp/tmpXyxNvC/___code___.py", line 2, in <module>
exec compile(u'C = LinearCode(G)
File "", line 1, in <module>
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/coding/linear_code.py", line 785, in __init__
facade_for = gen_mat.row(0).parent()
File "matrix_mod2_dense.pyx", line 576, in sage.matrix.matrix_mod2_dense.Matrix_mod2_dense.row (build/cythonized/sage/matrix/matrix_mod2_dense.c:5387)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 432, in VectorSpace
return FreeModule(K, rank=dimension, sparse=sparse, inner_product_matrix=inner_product_matrix)
File "factory.pyx", line 366, in sage.structure.factory.UniqueFactory.__call__ (build/cythonized/sage/structure/factory.c:1327)
File "factory.pyx", line 410, in sage.structure.factory.UniqueFactory.get_object (build/cythonized/sage/structure/factory.c:1679)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 380, in create_object
return FreeModule_ambient_field(base_ring, rank, sparse=sparse)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 4972, in __init__
FreeModule_ambient_pid.__init__(self, base_field, dimension, sparse=sparse)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 4893, in __init__
FreeModule_ambient_domain.__init__(self, base_ring=base_ring, rank=rank, sparse=sparse)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 4709, in __init__
FreeModule_ambient.__init__(self, base_ring, rank, sparse)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 4184, in __init__
FreeModule_generic.__init__(self, base_ring, rank=rank, degree=rank, sparse=sparse)
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 714, in __init__
self.element_class()
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 896, in element_class
C = element_class(self.base_ring(), self.is_sparse())
File "/usr/local/sage/local/lib/python2.7/site-packages/sage/modules/free_module.py", line 6721, in element_class
import sage.modules.vector_real_double_dense
File "vector_real_double_dense.pyx", line 1, in init sage.modules.vector_real_double_dense (build/cythonized/sage/modules/vector_real_double_dense.c:5611)
File "__init__.pxd", line 155, in init sage.modules.vector_double_dense (build/cythonized/sage/modules/vector_double_dense.c:11813)
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/__init__.py", line 153, in <module>
from . import add_newdocs
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/add_newdocs.py", line 13, in <module>
from numpy.lib import add_newdoc
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/lib/__init__.py", line 18, in <module>
from .polynomial import *
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/lib/polynomial.py", line 19, in <module>
from numpy.linalg import eigvals, lstsq, inv
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/linalg/__init__.py", line 50, in <module>
from .linalg import *
File "/usr/local/sage/local/lib/python2.7/site-packages/numpy/linalg/linalg.py", line 29, in <module>
from numpy.linalg import lapack_lite, _umath_linalg
ImportError: libgfortran.so.3: cannot open shared object file: No such file or directory
How can I solve this problem? I am new to sage!