From b0211f1096092d26a416511114b4884bad4d1675 Mon Sep 17 00:00:00 2001
From: Rafal Skolasinski <r.j.skolasinski@gmail.com>
Date: Wed, 11 Jul 2018 18:21:36 +0200
Subject: [PATCH] take site position from underlying discretizer lattice
Previously we were manually computing the position from
the site tag an an extra 'grid_spacing' parameter. Even
though we now have one additional Python function call,
using the position as determined by the underlying lattice
is less susceptible to bugs.
Closes #199.
---
kwant/continuum/discretizer.py | 14 ++++----------
kwant/continuum/tests/test_discretizer.py | 10 ++++++++++
2 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/kwant/continuum/discretizer.py b/kwant/continuum/discretizer.py
index bd05342b..baef963c 100644
--- a/kwant/continuum/discretizer.py
+++ b/kwant/continuum/discretizer.py
@@ -582,16 +582,13 @@ def _return_string(expr, coords):
return 'return {}'.format(output), map_func_calls, const_symbols, _cache
-def _assign_symbols(map_func_calls, grid_spacing,
- coords, onsite):
+def _assign_symbols(map_func_calls, coords, onsite):
"""Generate a series of assignments.
Parameters
----------
map_func_calls : dict
mapping of function calls to assigned constants.
- grid_spacing : int or float
- Used to get site.pos from site.tag
coords : sequence of strings
If left as None coordinates will not be read from a site.
onsite : bool
@@ -606,8 +603,8 @@ def _assign_symbols(map_func_calls, grid_spacing,
if coords:
site = 'site' if onsite else 'site1'
- args = ', '.join(coords), str(grid_spacing), site
- lines.append('({}, ) = {} * {}.tag'.format(*args))
+ args = ', '.join(coords), site
+ lines.append('({}, ) = {}.pos'.format(*args))
for k, v in map_func_calls.items():
lines.append("{} = {}".format(v, _print_sympy(k)))
@@ -667,10 +664,7 @@ def _builder_value(expr, coords, grid_spacing, onsite,
else:
return complex(expr)
- lines = _assign_symbols(map_func_calls, onsite=onsite,
- grid_spacing=grid_spacing,
- coords=coords)
-
+ lines = _assign_symbols(map_func_calls, onsite=onsite, coords=coords)
lines.append(return_string)
separator = '\n '
diff --git a/kwant/continuum/tests/test_discretizer.py b/kwant/continuum/tests/test_discretizer.py
index 19ec7454..54c8da65 100644
--- a/kwant/continuum/tests/test_discretizer.py
+++ b/kwant/continuum/tests/test_discretizer.py
@@ -563,6 +563,16 @@ def test_grid_input(ham, grid_offset, offset, norbs):
assert tmp.lattice.norbs == norbs
+def test_grid_offset_passed_to_functions():
+ V = lambda x: x
+ grid = Monatomic([[1, ]], offset=[0.5, ])
+ tb = discretize('V(x)', 'x', grid=grid)
+ onsite = tb[tb.lattice(0)]
+ bools = [np.allclose(onsite(tb.lattice(i), V), V(tb.lattice(i).pos))
+ for i in [0, 1, 5]]
+ assert all(bools)
+
+
@pytest.mark.parametrize("ham, coords, grid", [
("k_x", None, Monatomic([[1, 0]])),
("k_x", 'xy', Monatomic([[1, 0]])),
--
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