Merge branch 'issue-48' into 'master'

attempt to fix E

Closes #48

See merge request !28

.gitlab-ci.yml

@@ -12,26 +12,26 @@ image: gitlab.kwant-project.org:5005/qt/research-docker
 
 test minimal requirements:
   script:
-    - conda env create -f environment-minimal.yml
+    - mamba env create -f environment-minimal.yml
     - source activate qsymm-minimal
     - py.test qsymm/ --cov=qsymm --verbose --cov-report term
   stage: test
 
 test latest requirements:
   script:
-    - conda env create -f environment-latest.yml
+    - mamba env create -f environment-latest.yml
     - source activate qsymm-latest
     - py.test qsymm/ --cov=qsymm --verbose --cov-report term
   stage: test
 
 test kwant against latest qsymm:
   script:
-    - conda env create -f environment-latest.yml
+    - mamba env create -f environment-latest.yml
     - source activate qsymm-latest
     # Get bleeding-edge Kwant
-    - conda install cython
+    - mamba install cython
     - pip install .  # need to install qsymm so that the kwant test can find it
-    - pip install git+https://gitlab.kwant-project.org/kwant/kwant.git
+    - pip install git+https://gitlab.kwant-project.org/kwant/kwant.git@stable
     - export KWANT_QSYMM_PATH=$(python -c "$KWANT_QSYMM_TEST_PATH_SCRIPT")
     - py.test $KWANT_QSYMM_PATH
   stage: test

environment-latest.yml

@@ -2,7 +2,7 @@ name: qsymm-latest
 channels:
     - conda-forge
 dependencies:
-    - python=3.10
+    - python=3.11
     - numpy
     - scipy
     - sympy

qsymm/kwant_continuum.py

@@ -51,6 +51,7 @@ import warnings
 
 momentum_operators = sympy.symbols('k_x k_y k_z', commutative=False)
 position_operators = sympy.symbols('x y z', commutative=False)
+e = sympy.symbols('e', positive=True)
 
 pauli = [sympy.eye(2), _msigma(1), _msigma(2), _msigma(3)]
 
@@ -217,6 +218,8 @@ def sympify(expr, locals=None):
         # sympify we are getting list of sympy objects, so we call sympify
         # second time to obtain ``sympy`` matrices.
         hamiltonian = sympy.sympify(hamiltonian)
+        # A workaround for qsymm issue #48
+        hamiltonian = hamiltonian.subs(sympy.sympify('e'), e)
     finally:
         if stored_value is not None:
             converter[list] = stored_value

qsymm/model.py

@@ -19,8 +19,8 @@ from . import kwant_continuum
 _commutative_momenta = [kwant_continuum.make_commutative(k, k)
            for k in kwant_continuum.momentum_operators]
 
-e = kwant_continuum.sympify('e')
-I = kwant_continuum.sympify('I')  # noqa: E741
+e = kwant_continuum.e
+I = sympy.I  # noqa: E741
 
 
 def substitute_exponents(expr):
@@ -671,7 +671,7 @@ class Model(UserDict):
         an error is thrown.
         """
         # Replace 'e' with the numerical value
-        expr = self.tosympy(nsimplify=nsimplify).subs({'e': np.e})
+        expr = self.tosympy(nsimplify=nsimplify).subs({e: np.e})
         # Needed if expr is an array with 1 element, because .tosympy
         # returns a scalar then.
         try:
@@ -990,7 +990,7 @@ def _find_momenta(momenta):
 
 @lru_cache(maxsize=1000)
 def _symbol_normalizer(key):
-    return sympy.expand_power_exp(sympy.sympify(key))
+    return sympy.expand_power_exp(sympy.sympify(key, locals={'e': e}))
 
 
 @lru_cache(maxsize=1000)