@@ -381,18 +381,13 @@ def search_mumps():

     libmumps-scotch-dev and the MUMPS binaries in the conda-forge channel."""

     lib_sets = [

         # Debian

-        ['zmumps_scotch', 'mumps_common_scotch', 'mpiseq_scotch'],

+        ['zmumps_scotch', 'mumps_common_scotch', 'mpiseq_scotch',

+         'pord', 'gfortran'],

         # Conda (via conda-forge).

-        # TODO: remove dependency libs (scotch, metis...) when conda-forge

-        # packaged mumps/scotch are built as properly linked shared libs

-        # 'openblas' provides Lapack and BLAS symbols

-        ['zmumps', 'mumps_common', 'metis', 'esmumps', 'scotch',

-         'scotcherr', 'mpiseq', 'openblas'],

+        ['zmumps_seq', 'mumps_common_seq'],

     ]

-    common_libs = ['pord', 'gfortran']

-

     for libs in lib_sets:

-        found_libs = search_libs(libs + common_libs)

+        found_libs = search_libs(libs)

         if found_libs:

             return found_libs

     return []

@@ -585,7 +585,8 @@ def main():

                             'tinyarray >= 1.2'],

           extras_require={

               # The oldest versions between: Debian stable, Ubuntu LTS

-              'plotting': 'matplotlib >= 2.1.1',

+              'plotting': ['matplotlib >= 2.1.1',

+                           'plotly >= 2.2.2'],

               'continuum': 'sympy >= 1.1.1',

               # qsymm is only packaged on PyPI

               'qsymm': 'qsymm >= 1.2.6',

@@ -517,7 +517,7 @@ def maybe_add_numpy_include(exts):

 def main():

-    check_python_version((3, 5))

+    check_python_version((3, 6))

     check_versions()

     exts = collections.OrderedDict([

@@ -581,12 +581,12 @@ def main():

                     'build_ext': build_ext,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy >= 1.11.0', 'scipy >= 0.17.0',

+          install_requires=['numpy >= 1.13.3', 'scipy >= 0.19.1',

                             'tinyarray >= 1.2'],

           extras_require={

               # The oldest versions between: Debian stable, Ubuntu LTS

-              'plotting': 'matplotlib >= 1.5.1',

-              'continuum': 'sympy >= 0.7.6',

+              'plotting': 'matplotlib >= 2.1.1',

+              'continuum': 'sympy >= 1.1.1',

               # qsymm is only packaged on PyPI

               'qsymm': 'qsymm >= 1.2.6',

           },

@@ -588,7 +588,7 @@ def main():

               'plotting': 'matplotlib >= 1.5.1',

               'continuum': 'sympy >= 0.7.6',

               # qsymm is only packaged on PyPI

-              'qsymm': 'qsymm >= 1.2.4',

+              'qsymm': 'qsymm >= 1.2.6',

           },

           classifiers=[c.strip() for c in classifiers.split('\n')])

@@ -588,7 +588,7 @@ def main():

               'plotting': 'matplotlib >= 1.5.1',

               'continuum': 'sympy >= 0.7.6',

               # qsymm is only packaged on PyPI

-              'qsymm': 'qsymm >= 1.1.2',

+              'qsymm': 'qsymm >= 1.2.4',

           },

           classifiers=[c.strip() for c in classifiers.split('\n')])

@@ -562,6 +562,7 @@ def main():

         Operating System :: MacOS :: MacOS X

         Operating System :: Microsoft :: Windows"""

+    packages = find_packages('.')

     setup(name='kwant',

           version=version,

           author='C. W. Groth (CEA), M. Wimmer, '

@@ -573,7 +574,8 @@ def main():

           platforms=["Unix", "Linux", "Mac OS-X", "Windows"],

           url="http://kwant-project.org/",

           license="BSD",

-          packages=find_packages('.'),

+          packages=packages,

+          package_data={p: ['*.pxd', '*.h'] for p in packages},

           cmdclass={'build': build,

                     'sdist': sdist,

                     'build_ext': build_ext,

@@ -270,9 +270,8 @@ class sdist(sdist_orig):

     sub_commands = [('build', None)] + sdist_orig.sub_commands

     def run(self):

-        """

-        Create MANIFEST.in from git if possible, otherwise check that MANIFEST.in

-        is present.

+        """Create MANIFEST.in from git if possible, otherwise check that

+        MANIFEST.in is present.

         Right now (2015) generating MANIFEST.in seems to be the only way to

         include files in the source distribution that setuptools does not think

@@ -1,6 +1,6 @@

 #!/usr/bin/env python3

-# Copyright 2011-2017 Kwant authors.

+# Copyright 2011-2018 Kwant authors.

 #

 # This file is part of Kwant.  It is subject to the license terms in the file

 # LICENSE.rst found in the top-level directory of this distribution and at

@@ -586,6 +586,8 @@ def main():

               # The oldest versions between: Debian stable, Ubuntu LTS

               'plotting': 'matplotlib >= 1.5.1',

               'continuum': 'sympy >= 0.7.6',

+              # qsymm is only packaged on PyPI

+              'qsymm': 'qsymm >= 1.1.2',

           },

           classifiers=[c.strip() for c in classifiers.split('\n')])

@@ -532,6 +532,8 @@ def main():

          dict(sources=['kwant/graph/core.pyx'],

               depends=['kwant/graph/core.pxd', 'kwant/graph/defs.h',

                        'kwant/graph/defs.pxd'])),

+        ('kwant.graph.dijkstra',

+         dict(sources=['kwant/graph/dijkstra.pyx'])),

         ('kwant.linalg.lapack',

          dict(sources=['kwant/linalg/lapack.pyx'])),

         ('kwant.linalg._mumps',

@@ -167,7 +167,7 @@ def init_cython():

     global cythonize, cython_help

     cython_option = '--cython'

-    required_cython_version = (0, 22)

+    required_cython_version = (0, 24)

     try:

         sys.argv.remove(cython_option)

         cythonize = True

@@ -533,20 +533,6 @@ def main():

          dict(sources=['kwant/graph/core.pyx'],

               depends=['kwant/graph/core.pxd', 'kwant/graph/defs.h',

                        'kwant/graph/defs.pxd'])),

-        ('kwant.graph.utils',

-         dict(sources=['kwant/graph/utils.pyx'],

-              depends=['kwant/graph/defs.h', 'kwant/graph/defs.pxd',

-                       'kwant/graph/core.pxd'])),

-        ('kwant.graph.slicer',

-         dict(sources=['kwant/graph/slicer.pyx',

-                       'kwant/graph/c_slicer/partitioner.cc',

-                       'kwant/graph/c_slicer/slicer.cc'],

-              depends=['kwant/graph/defs.h', 'kwant/graph/defs.pxd',

-                       'kwant/graph/core.pxd', 'kwant/graph/c_slicer.pxd',

-                       'kwant/graph/c_slicer/bucket_list.h',

-                       'kwant/graph/c_slicer/graphwrap.h',

-                       'kwant/graph/c_slicer/partitioner.h',

-                       'kwant/graph/c_slicer/slicer.h'])),

         ('kwant.linalg.lapack',

          dict(sources=['kwant/linalg/lapack.pyx'])),

         ('kwant.linalg._mumps',

@@ -15,7 +15,7 @@ import sys

 import re

 import os

 import glob

-import imp

+import importlib

 import subprocess

 import configparser

 import collections

@@ -123,10 +123,9 @@ def check_versions():

     # Let Kwant itself determine its own version.  We cannot simply import

     # kwant, as it is not built yet.

-    _dont_write_bytecode_saved = sys.dont_write_bytecode

-    sys.dont_write_bytecode = True

-    version_module = imp.load_source('version', 'kwant/version.py')

-    sys.dont_write_bytecode = _dont_write_bytecode_saved

+    spec = importlib.util.spec_from_file_location('version', 'kwant/version.py')

+    version_module = importlib.util.module_from_spec(spec)

+    spec.loader.exec_module(version_module)

     version_module.ensure_python()

     version = version_module.version

@@ -505,6 +505,20 @@ def maybe_cythonize(exts):

     return result

+def maybe_add_numpy_include(exts):

+    # Add NumPy header path to include_dirs of all the extensions.

+    try:

+        import numpy

+    except ImportError:

+        print(banner(' Caution '), 'NumPy header directory cannot be determined'

+              ' ("import numpy" failed).', banner(), sep='\n', file=sys.stderr)

+    else:

+        numpy_include = numpy.get_include()

+        for ext in exts.values():

+            ext.setdefault('include_dirs', []).append(numpy_include)

+    return exts

+

+

 def main():

     check_python_version((3, 5))

     check_versions()

@@ -540,17 +554,6 @@ def main():

          dict(sources=['kwant/linalg/_mumps.pyx'],

               depends=['kwant/linalg/cmumps.pxd']))])

-    # Add NumPy header path to include_dirs of all the extensions.

-    try:

-        import numpy

-    except ImportError:

-        print(banner(' Caution '), 'NumPy header directory cannot be determined'

-              ' ("import numpy" failed).', banner(), sep='\n', file=sys.stderr)

-    else:

-        numpy_include = numpy.get_include()

-        for ext in exts.values():

-            ext.setdefault('include_dirs', []).append(numpy_include)

-

     aliases = [('mumps', 'kwant.linalg._mumps')]

     init_cython()

@@ -559,6 +562,7 @@ def main():

     build_summary = []

     exts = configure_extensions(exts, aliases, build_summary)

     exts = configure_special_extensions(exts, build_summary)

+    exts = maybe_add_numpy_include(exts)

     exts = maybe_cythonize(exts)

     classifiers = """\

@@ -250,8 +250,7 @@ def git_lsfiles():

 # Make the command "sdist" depend on "build".  This verifies that the

 # distribution in the current state actually builds.  It also makes sure that

-# the Cython-made C files and the tutorial will be included in the source

-# distribution and that they will be up-to-date.

+# the Cython-made C files will be up-to-date and included in the source.

 class sdist(sdist_orig):

     sub_commands = [('build', None)] + sdist_orig.sub_commands

@@ -388,8 +388,9 @@ def search_mumps():

         # Conda (via conda-forge).

         # TODO: remove dependency libs (scotch, metis...) when conda-forge

         # packaged mumps/scotch are built as properly linked shared libs

+        # 'openblas' provides Lapack and BLAS symbols

         ['zmumps', 'mumps_common', 'metis', 'esmumps', 'scotch',

-         'scotcherr', 'mpiseq'],

+         'scotcherr', 'mpiseq', 'openblas'],

     ]

     common_libs = ['pord', 'gfortran']

@@ -400,34 +401,7 @@ def search_mumps():

     return []

-def search_lapack():

-    """Return the BLAS variant that is installed."""

-    lib_sets = [

-        # Debian

-        ['blas', 'lapack'],

-        # Conda (via conda-forge). Openblas contains lapack symbols

-        ['openblas', 'gfortran'],

-    ]

-

-    for libs in lib_sets:

-        found_libs = search_libs(libs)

-        if found_libs:

-            return found_libs

-

-    print('Error: BLAS/LAPACK are required but were not found.',

-          file=sys.stderr)

-    sys.exit(1)

-

-

 def configure_special_extensions(exts, build_summary):

-    #### Special config for LAPACK.

-    lapack = exts['kwant.linalg.lapack']

-    if 'libraries' in lapack:

-        build_summary.append('User-configured LAPACK and BLAS')

-    else:

-        lapack['libraries'] = search_lapack()

-        build_summary.append('Default LAPACK and BLAS')

-

     #### Special config for MUMPS.

     mumps = exts['kwant.linalg._mumps']

     if 'libraries' in mumps:

@@ -442,12 +416,6 @@ def configure_special_extensions(exts, build_summary):

             del exts['kwant.linalg._mumps']

             build_summary.append('No MUMPS support')

-    if mumps:

-        # Copy config from LAPACK.

-        for key, value in lapack.items():

-            if key not in ['sources', 'depends']:

-                mumps.setdefault(key, []).extend(value)

-

     return exts

@@ -567,8 +535,7 @@ def main():

                        'kwant/graph/c_slicer/partitioner.h',

                        'kwant/graph/c_slicer/slicer.h'])),

         ('kwant.linalg.lapack',

-         dict(sources=['kwant/linalg/lapack.pyx'],

-              depends=['kwant/linalg/f_lapack.pxd'])),

+         dict(sources=['kwant/linalg/lapack.pyx'])),

         ('kwant.linalg._mumps',

          dict(sources=['kwant/linalg/_mumps.pyx'],

               depends=['kwant/linalg/cmumps.pxd']))])

@@ -584,8 +551,7 @@ def main():

         for ext in exts.values():

             ext.setdefault('include_dirs', []).append(numpy_include)

-    aliases = [('lapack', 'kwant.linalg.lapack'),

-               ('mumps', 'kwant.linalg._mumps')]

+    aliases = [('mumps', 'kwant.linalg._mumps')]

     init_cython()

@@ -372,9 +372,8 @@ def search_mumps():

         # Conda (via conda-forge).

         # TODO: remove dependency libs (scotch, metis...) when conda-forge

         # packaged mumps/scotch are built as properly linked shared libs

-        # 'openblas' provides Lapack and BLAS symbols

         ['zmumps', 'mumps_common', 'metis', 'esmumps', 'scotch',

-         'scotcherr', 'mpiseq', 'openblas'],

+         'scotcherr', 'mpiseq'],

     ]

     common_libs = ['pord', 'gfortran']

@@ -385,7 +384,34 @@ def search_mumps():

     return []

+def search_lapack():

+    """Return the BLAS variant that is installed."""

+    lib_sets = [

+        # Debian

+        ['blas', 'lapack'],

+        # Conda (via conda-forge). Openblas contains lapack symbols

+        ['openblas', 'gfortran'],

+    ]

+

+    for libs in lib_sets:

+        found_libs = search_libs(libs)

+        if found_libs:

+            return found_libs

+

+    print('Error: BLAS/LAPACK are required but were not found.',

+          file=sys.stderr)

+    sys.exit(1)

+

+

 def configure_special_extensions(exts, build_summary):

+    #### Special config for LAPACK.

+    lapack = exts['kwant.linalg.lapack']

+    if 'libraries' in lapack:

+        build_summary.append('User-configured LAPACK and BLAS')

+    else:

+        lapack['libraries'] = search_lapack()

+        build_summary.append('Default LAPACK and BLAS')

+

     #### Special config for MUMPS.

     mumps = exts['kwant.linalg._mumps']

     if 'libraries' in mumps:

@@ -400,6 +426,12 @@ def configure_special_extensions(exts, build_summary):

             del exts['kwant.linalg._mumps']

             build_summary.append('No MUMPS support')

+    if mumps:

+        # Copy config from LAPACK.

+        for key, value in lapack.items():

+            if key not in ['sources', 'depends']:

+                mumps.setdefault(key, []).extend(value)

+

     return exts

@@ -518,7 +550,8 @@ def main():

                        'kwant/graph/c_slicer/partitioner.h',

                        'kwant/graph/c_slicer/slicer.h'])),

         ('kwant.linalg.lapack',

-         dict(sources=['kwant/linalg/lapack.pyx'])),

+         dict(sources=['kwant/linalg/lapack.pyx'],

+              depends=['kwant/linalg/f_lapack.pxd'])),

         ('kwant.linalg._mumps',

          dict(sources=['kwant/linalg/_mumps.pyx'],

               depends=['kwant/linalg/cmumps.pxd']))])

@@ -534,7 +567,8 @@ def main():

         for ext in exts.values():

             ext.setdefault('include_dirs', []).append(numpy_include)

-    aliases = [('mumps', 'kwant.linalg._mumps')]

+    aliases = [('lapack', 'kwant.linalg.lapack'),

+               ('mumps', 'kwant.linalg._mumps')]

     init_cython()

@@ -372,8 +372,9 @@ def search_mumps():

         # Conda (via conda-forge).

         # TODO: remove dependency libs (scotch, metis...) when conda-forge

         # packaged mumps/scotch are built as properly linked shared libs

+        # 'openblas' provides Lapack and BLAS symbols

         ['zmumps', 'mumps_common', 'metis', 'esmumps', 'scotch',

-         'scotcherr', 'mpiseq'],

+         'scotcherr', 'mpiseq', 'openblas'],

     ]

     common_libs = ['pord', 'gfortran']

@@ -384,34 +385,7 @@ def search_mumps():

     return []

-def search_lapack():

-    """Return the BLAS variant that is installed."""

-    lib_sets = [

-        # Debian

-        ['blas', 'lapack'],

-        # Conda (via conda-forge). Openblas contains lapack symbols

-        ['openblas', 'gfortran'],

-    ]

-

-    for libs in lib_sets:

-        found_libs = search_libs(libs)

-        if found_libs:

-            return found_libs

-

-    print('Error: BLAS/LAPACK are required but were not found.',

-          file=sys.stderr)

-    sys.exit(1)

-

-

 def configure_special_extensions(exts, build_summary):

-    #### Special config for LAPACK.

-    lapack = exts['kwant.linalg.lapack']

-    if 'libraries' in lapack:

-        build_summary.append('User-configured LAPACK and BLAS')

-    else:

-        lapack['libraries'] = search_lapack()

-        build_summary.append('Default LAPACK and BLAS')

-

     #### Special config for MUMPS.

     mumps = exts['kwant.linalg._mumps']

     if 'libraries' in mumps:

@@ -426,12 +400,6 @@ def configure_special_extensions(exts, build_summary):

             del exts['kwant.linalg._mumps']

             build_summary.append('No MUMPS support')

-    if mumps:

-        # Copy config from LAPACK.

-        for key, value in lapack.items():

-            if key not in ['sources', 'depends']:

-                mumps.setdefault(key, []).extend(value)

-

     return exts

@@ -550,8 +518,7 @@ def main():

                        'kwant/graph/c_slicer/partitioner.h',

                        'kwant/graph/c_slicer/slicer.h'])),

         ('kwant.linalg.lapack',

-         dict(sources=['kwant/linalg/lapack.pyx'],

-              depends=['kwant/linalg/f_lapack.pxd'])),

+         dict(sources=['kwant/linalg/lapack.pyx'])),

         ('kwant.linalg._mumps',

          dict(sources=['kwant/linalg/_mumps.pyx'],

               depends=['kwant/linalg/cmumps.pxd']))])

@@ -567,8 +534,7 @@ def main():

         for ext in exts.values():

             ext.setdefault('include_dirs', []).append(numpy_include)

-    aliases = [('lapack', 'kwant.linalg.lapack'),

-               ('mumps', 'kwant.linalg._mumps')]

+    aliases = [('mumps', 'kwant.linalg._mumps')]

     init_cython()

@@ -227,40 +227,7 @@ Build configuration was:

 """

-class build_tut(Command):

-    description = "build the tutorial scripts"

-    user_options = []

-

-    def initialize_options(self):

-        pass

-

-    def finalize_options(self):

-        pass

-

-    def run(self):

-        tut_dir = 'tutorial'

-        if not os.path.exists(tut_dir):

-            os.mkdir(tut_dir)

-        for in_fname in glob.glob('doc/source/tutorial/*.py'):

-            basename = os.path.basename(in_fname)

-            if basename == 'faq.py':

-                # The FAQ script is not meant as an example.

-                continue

-            out_fname = os.path.join(tut_dir, basename)

-            with open(in_fname, 'rb') as in_file:

-                with open(out_fname, 'wb') as out_file:

-                    for line in in_file:

-                        if not line.startswith(b'#HIDDEN'):

-                            out_file.write(line)

-

-

-# Our version of the "build" command also makes sure the tutorial is made.

-# Even though the tutorial is not necessary for installation, and "build" is

-# supposed to make everything needed to install, this is a robust way to ensure

-# that the tutorial is present.

 class build(build_orig):

-    sub_commands = [('build_tut', None)] + build_orig.sub_commands

-

     def run(self):

         super().run()

         write_version(os.path.join(self.build_lib, *STATIC_VERSION_PATH))

@@ -638,7 +605,6 @@ def main():

           cmdclass={'build': build,

                     'sdist': sdist,

                     'build_ext': build_ext,

-                    'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

           install_requires=['numpy >= 1.8.1', 'scipy >= 0.14',

@@ -242,7 +242,11 @@ class build_tut(Command):

         if not os.path.exists(tut_dir):

             os.mkdir(tut_dir)

         for in_fname in glob.glob('doc/source/tutorial/*.py'):

-            out_fname = os.path.join(tut_dir, os.path.basename(in_fname))

+            basename = os.path.basename(in_fname)

+            if basename == 'faq.py':

+                # The FAQ script is not meant as an example.

+                continue

+            out_fname = os.path.join(tut_dir, basename)

             with open(in_fname, 'rb') as in_file:

                 with open(out_fname, 'wb') as out_file:

                     for line in in_file:

@@ -124,6 +124,16 @@ def configure_extensions(exts, aliases=(), build_summary=None):

     return exts

+def check_python_version(min_version):

+    installed_version = sys.version_info[:3]

+    if installed_version < min_version:

+        print('Error: Python {} required, but {} is installed'.format(

+              '.'.join(map(str, min_version)),

+              '.'.join(map(str, installed_version)))

+        )

+        sys.exit(1)

+

+

 def check_versions():

     global version, version_is_from_git

@@ -557,6 +567,7 @@ def maybe_cythonize(exts):

 def main():

+    check_python_version((3, 5))

     check_versions()

     exts = collections.OrderedDict([

@@ -643,11 +643,11 @@ def main():

                     'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy >= 1.8.1', 'scipy >= 0.14',

+          install_requires=['numpy >= 1.11.0', 'scipy >= 0.17.0',

                             'tinyarray >= 1.2'],

           extras_require={

-              'plotting': 'matplotlib >= 1.4.2',

-              # Ubuntu 16.04 is the oldest supported distro with python3-sympy

+              # The oldest versions between: Debian stable, Ubuntu LTS

+              'plotting': 'matplotlib >= 1.5.1',

               'continuum': 'sympy >= 0.7.6',

           },

           classifiers=[c.strip() for c in classifiers.split('\n')])

@@ -45,10 +45,12 @@ def configure_extensions(exts, aliases=(), build_summary=None):

     #### Determine the name of the configuration file.

     config_file_option = '--configfile'

+    config_file_option_present = False

     # Handle command line option

     for i, opt in enumerate(sys.argv):

         if not opt.startswith(config_file_option):

             continue

+        config_file_option_present = True

         l, _, config_file = opt.partition('=')

         if l != config_file_option or not config_file:

             print('Error: Expecting {}=PATH'.format(config_file_option),

@@ -66,6 +68,10 @@ def configure_extensions(exts, aliases=(), build_summary=None):

             configs.read_file(f)

     except IOError:

         config_file_present = False

+        if config_file_option_present:

+            print("Error: '{}' option was provided, but '{}' does not exist"

+                  .format(config_file_option, config_file))

+            sys.exit(1)

     else:

         config_file_present = True

@@ -364,7 +364,7 @@ def write_version(fname):

 def long_description():

     text = []

     try:

-        with open('README.rst') as f:

+        with open('README.rst', encoding='utf8') as f:

             for line in f:

                 if line.startswith('See also in this directory:'):

                     break

@@ -243,10 +243,10 @@ class build_tut(Command):

             os.mkdir(tut_dir)

         for in_fname in glob.glob('doc/source/tutorial/*.py'):

             out_fname = os.path.join(tut_dir, os.path.basename(in_fname))

-            with open(in_fname) as in_file:

-                with open(out_fname, 'w') as out_file:

+            with open(in_fname, 'rb') as in_file:

+                with open(out_fname, 'wb') as out_file:

                     for line in in_file:

-                        if not line.startswith('#HIDDEN'):

+                        if not line.startswith(b'#HIDDEN'):

                             out_file.write(line)

@@ -637,8 +637,8 @@ def main():

                     'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy >= 1.8.1', 'scipy >= 0.14.0',

-                            'tinyarray >= 1.2.0'],

+          install_requires=['numpy >= 1.8.1', 'scipy >= 0.14',

+                            'tinyarray >= 1.2'],

           extras_require={

               'plotting': 'matplotlib >= 1.4.2',

               # Ubuntu 16.04 is the oldest supported distro with python3-sympy

@@ -1,6 +1,6 @@

 #!/usr/bin/env python3

-# Copyright 2011-2016 Kwant authors.

+# Copyright 2011-2017 Kwant authors.

 #

 # This file is part of Kwant.  It is subject to the license terms in the file

 # LICENSE.rst found in the top-level directory of this distribution and at

@@ -637,9 +637,10 @@ def main():

                     'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray >= 1.2.0'],

+          install_requires=['numpy >= 1.8.1', 'scipy >= 0.14.0',

+                            'tinyarray >= 1.2.0'],

           extras_require={

-              'plotting': 'matplotlib >= 1.3.1',

+              'plotting': 'matplotlib >= 1.4.2',

               # Ubuntu 16.04 is the oldest supported distro with python3-sympy

               'continuum': 'sympy >= 0.7.6',

           },

@@ -637,7 +637,7 @@ def main():

                     'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray'],

+          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray >= 1.2.0'],

           extras_require={

               'plotting': 'matplotlib >= 1.3.1',

               # Ubuntu 16.04 is the oldest supported distro with python3-sympy

@@ -51,7 +51,7 @@ def configure_extensions(exts, aliases=(), build_summary=None):

             continue

         l, _, config_file = opt.partition('=')

         if l != config_file_option or not config_file:

-            print('error: Expecting {}=PATH'.format(config_file_option),

+            print('Error: Expecting {}=PATH'.format(config_file_option),

                   file=sys.stderr)

             sys.exit(1)

         sys.argv.pop(i)

@@ -426,7 +426,10 @@ def search_lapack():

         found_libs = search_libs(libs)

         if found_libs:

             return found_libs

-    return []

+

+    print('Error: BLAS/LAPACK are required but were not found.',

+          file=sys.stderr)

+    sys.exit(1)

 def configure_special_extensions(exts, build_summary):

@@ -634,9 +634,9 @@ def main():

                     'build_tut': build_tut,

                     'test': test},

           ext_modules=exts,

-          install_requires=['numpy > 1.6.1', 'scipy >= 0.11.0', 'tinyarray'],

+          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray'],

           extras_require={

-              'plotting': 'matplotlib >= 1.2',

+              'plotting': 'matplotlib >= 1.3.1',

               # Ubuntu 16.04 is the oldest supported distro with python3-sympy

               'continuum': 'sympy >= 0.7.6',

           },

@@ -12,19 +12,6 @@ from __future__ import print_function

 import sys

-

-def ensure_python(required_version):

-    v = sys.version_info

-    if v[:3] < required_version:

-        error = "This version of Kwant requires Python {} or above.".format(

-            ".".join(str(p) for p in required_version))

-        if v[0] == 2:

-            error += "\nKwant 1.1 is the last version to support Python 2."

-        print(error, file=sys.stderr)

-        sys.exit(1)

-

-ensure_python((3, 4))

-

 import re

 import os

 import glob

@@ -131,18 +118,19 @@ def configure_extensions(exts, aliases=(), build_summary=None):

     return exts

-def get_version():

+def check_versions():

     global version, version_is_from_git

     # Let Kwant itself determine its own version.  We cannot simply import

     # kwant, as it is not built yet.

     _dont_write_bytecode_saved = sys.dont_write_bytecode

     sys.dont_write_bytecode = True

-    _common = imp.load_source('_common', 'kwant/_common.py')

+    version_module = imp.load_source('version', 'kwant/version.py')

     sys.dont_write_bytecode = _dont_write_bytecode_saved

-    version = _common.version

-    version_is_from_git = _common.version_is_from_git

+    version_module.ensure_python()

+    version = version_module.version

+    version_is_from_git = version_module.version_is_from_git

 def init_cython():

@@ -560,6 +548,8 @@ def maybe_cythonize(exts):

 def main():

+    check_versions()

+

     exts = collections.OrderedDict([

         ('kwant._system',

          dict(sources=['kwant/_system.pyx'],

@@ -606,7 +596,6 @@ def main():

     aliases = [('lapack', 'kwant.linalg.lapack'),

                ('mumps', 'kwant.linalg._mumps')]

-    get_version()

     init_cython()

     global build_summary

@@ -646,7 +646,11 @@ def main():

                     'test': test},

           ext_modules=exts,

           install_requires=['numpy > 1.6.1', 'scipy >= 0.11.0', 'tinyarray'],

-          extras_require={'plotting': 'matplotlib >= 1.2'},

+          extras_require={

+              'plotting': 'matplotlib >= 1.2',

+              # Ubuntu 16.04 is the oldest supported distro with python3-sympy

+              'continuum': 'sympy >= 0.7.6',

+          },

           classifiers=[c.strip() for c in classifiers.split('\n')])

 if __name__ == '__main__':

@@ -388,15 +388,7 @@ def long_description():

     return '\n'.join(text)

-def search_mumps():

-    """Return the configuration for MUMPS if it is available in a known way.

-

-    This is known to work with the MUMPS provided by the Debian package

-    libmumps-scotch-dev."""

-

-    libs = ['zmumps_scotch', 'mumps_common_scotch', 'pord', 'mpiseq_scotch',

-            'gfortran']

-

+def search_libs(libs):

     cmd = ['gcc']

     cmd.extend(['-l' + lib for lib in libs])

     cmd.extend(['-o/dev/null', '-xc', '-'])

@@ -407,8 +399,46 @@ def search_mumps():

     else:

         p.communicate(input=b'int main() {}\n')

         if p.wait() == 0:

-            return {'libraries': libs}

-    return {}

+            return libs

+

+

+def search_mumps():

+    """Return the configuration for MUMPS if it is available in a known way.

+

+    This is known to work with the MUMPS provided by the Debian package