pep8 and typo fix for tutorials

doc/source/images/2-quantum_well.py.diff

@@ -8,7 +8,7 @@
  
  # global variable governing the behavior of potential() in
  # make_system()
-@@ -75,19 +76,26 @@
+@@ -76,19 +77,26 @@
          smatrix = kwant.solve(sys, energy)
          data.append(smatrix.transmission(1, 0))
  

doc/source/images/2-spin_orbit.py.diff

@@ -8,7 +8,7 @@
  
  # define Pauli-matrices for convenience
  sigma_0 = numpy.eye(2)
-@@ -72,19 +73,25 @@
+@@ -73,19 +74,25 @@
          smatrix = kwant.solve(sys, energy)
          data.append(smatrix.transmission(1, 0))
  

doc/source/images/4-graphene.py.diff

@@ -50,10 +50,10 @@
 -    pyplot.figure()
 +    fig = pyplot.figure()
      pyplot.plot(momenta, energy_list)
--    pyplot.xlabel("momentum [in untis of (lattice constant)^-1]")
+-    pyplot.xlabel("momentum [in units of (lattice constant)^-1]")
 -    pyplot.ylabel("energy [in units of t]")
 -    pyplot.show()
-+    pyplot.xlabel("momentum [in untis of (lattice constant)^-1]",
++    pyplot.xlabel("momentum [in units of (lattice constant)^-1]",
 +                 fontsize=latex.mpl_label_size)
 +    pyplot.ylabel("energy [in units of t]",
 +                 fontsize=latex.mpl_label_size)

doc/source/images/5-superconductor_band_structure.py.diff

 --- original
 +++ modified
-@@ -17,6 +17,7 @@
+@@ -16,6 +16,7 @@
  
  # For plotting
  from matplotlib import pyplot
@@ -8,7 +8,7 @@
  
  tau_x = np.array([[0, 1], [1, 0]])
  tau_z = np.array([[1, 0], [0, -1]])
-@@ -47,12 +48,20 @@
+@@ -46,12 +47,20 @@
      # the bandstructure
      energy_list = [lead.energies(k) for k in momenta]
  

doc/source/tutorial/1-quantum_wire_revisited.py

@@ -59,10 +59,10 @@ def make_system(a=1, t=1.0, W=10, L=30):
     sys.attach_lead(lead1)
 
     return sys
-
 #HIDDEN_END_yxot
-#HIDDEN_BEGIN_ayuk
 
+
+#HIDDEN_BEGIN_ayuk
 def plot_conductance(sys, energies):
     # Compute conductance
     data = []

doc/source/tutorial/2-quantum_well.py

@@ -19,6 +19,7 @@ from matplotlib import pyplot
 #HIDDEN_BEGIN_ehso
 pot = 0
 
+
 def make_system(a=1, t=1.0, W=10, L=30, L_well=10):
     # Start with an empty tight-binding system and a single square lattice.
     # `a` is the lattice constant (by default set to 1 for simplicity.

doc/source/tutorial/2-spin_orbit.py

@@ -73,6 +73,7 @@ def make_system(a=1, t=1.0, alpha=0.5, e_z=0.08, W=10, L=30):
 
     return sys
 
+
 def plot_conductance(sys, energies):
     # Compute conductance
     data = []

doc/source/tutorial/4-graphene.py

@@ -25,9 +25,9 @@ sin_30, cos_30 = (1 / 2, sqrt(3) / 2)
 graphene = kwant.make_lattice([(1, 0), (sin_30, cos_30)],
                               [(0, 0), (0, 1 / sqrt(3))])
 a, b = graphene.sublattices
-
 #HIDDEN_END_hnla
 
+
 #HIDDEN_BEGIN_shzy
 def make_system(r=10, w=2.0, pot=0.1):
 
@@ -135,7 +135,7 @@ def plot_bandstructure(flead, momenta):
 
     pyplot.figure()
     pyplot.plot(momenta, energy_list)
-    pyplot.xlabel("momentum [in untis of (lattice constant)^-1]")
+    pyplot.xlabel("momentum [in units of (lattice constant)^-1]")
     pyplot.ylabel("energy [in units of t]")
     pyplot.show()
 

doc/source/tutorial/5-superconductor_band_structure.py

@@ -13,7 +13,6 @@
 import kwant
 
 import numpy as np
-from math import pi
 
 # For plotting
 from matplotlib import pyplot