diff --git a/sumpy/expansion/__init__.py b/sumpy/expansion/__init__.py
index 5551537a78451f3d9dc5851cd1b83c7f0f428f4e..71af7eba265cfc044b352e8e6094fec65ecba28d 100644
--- a/sumpy/expansion/__init__.py
+++ b/sumpy/expansion/__init__.py
@@ -161,12 +161,13 @@ class ExpansionBase(object):
def __ne__(self, other):
return not self.__eq__(other)
- def get_kernel_derivative_taker(self, dvec, rscale=1):
+ def get_kernel_derivative_taker(self, dvec, rscale, sac):
"""Return a MiDerivativeTaker instance that supports taking
derivatives of the kernel with respect to dvec
"""
from sumpy.tools import MiDerivativeTaker
- return MiDerivativeTaker(self.kernel.get_expression(dvec), dvec, rscale)
+ return MiDerivativeTaker(self.kernel.get_expression(dvec), dvec, rscale,
+ sac)
# }}}
@@ -648,9 +649,10 @@ class LaplaceConformingVolumeTaylorExpansion(VolumeTaylorExpansionBase):
def __init__(self, kernel, order, use_rscale):
self.expansion_terms_wrangler_key = (order, kernel.dim)
- def get_kernel_derivative_taker(self, dvec, rscale=1):
+ def get_kernel_derivative_taker(self, dvec, rscale, sac):
from sumpy.tools import LaplaceDerivativeTaker
- return LaplaceDerivativeTaker(self.kernel.get_expression(dvec), dvec, rscale)
+ return LaplaceDerivativeTaker(self.kernel.get_expression(dvec), dvec,
+ rscale, sac)
class HelmholtzConformingVolumeTaylorExpansion(VolumeTaylorExpansionBase):
diff --git a/sumpy/expansion/local.py b/sumpy/expansion/local.py
index 032516efc3635a7d53c47bd4d0fdb62e2f3ef53f..c2947c695c56f63da0c1029629811dcad2925da1 100644
--- a/sumpy/expansion/local.py
+++ b/sumpy/expansion/local.py
@@ -124,7 +124,7 @@ class VolumeTaylorLocalExpansionBase(LocalExpansionBase):
from sumpy.tools import MiDerivativeTakerWrapper
result = []
- taker = self.get_kernel_derivative_taker(avec, rscale)
+ taker = self.get_kernel_derivative_taker(avec, rscale, sac)
expr_dict = {(0,)*self.dim: 1}
expr_dict = self.kernel.get_derivative_transformation_at_source(expr_dict)
pp_nderivatives = single_valued(sum(mi) for mi in expr_dict.keys())
@@ -215,7 +215,7 @@ class VolumeTaylorLocalExpansionBase(LocalExpansionBase):
# The vector has the kernel derivatives and depends only on the distance
# between the two centers
- taker = src_expansion.get_kernel_derivative_taker(dvec, src_rscale)
+ taker = src_expansion.get_kernel_derivative_taker(dvec, src_rscale, sac)
vector_stored = []
# Calculate the kernel derivatives for the compressed set
for term in \
diff --git a/sumpy/expansion/multipole.py b/sumpy/expansion/multipole.py
index de9aa500b0c19863ae0c539c0cf6ad4ae86e4ad6..fe8d30a19e380d90a19a62d08d85684e4db89587 100644
--- a/sumpy/expansion/multipole.py
+++ b/sumpy/expansion/multipole.py
@@ -25,7 +25,6 @@ THE SOFTWARE.
from six.moves import range, zip
import sumpy.symbolic as sym # noqa
-from sumpy.symbolic import vector_xreplace
from sumpy.expansion import (
ExpansionBase, VolumeTaylorExpansion, LaplaceConformingVolumeTaylorExpansion,
HelmholtzConformingVolumeTaylorExpansion,
@@ -88,7 +87,7 @@ class VolumeTaylorMultipoleExpansionBase(MultipoleExpansionBase):
if knl is None:
knl = self.kernel
- taker = self.get_kernel_derivative_taker(bvec, rscale)
+ taker = self.get_kernel_derivative_taker(bvec, rscale, sac)
expr_dict = {(0,)*self.dim: 1}
expr_dict = knl.get_derivative_transformation_at_target(expr_dict)
pp_nderivatives = single_valued(sum(mi) for mi in expr_dict.keys())
diff --git a/sumpy/tools.py b/sumpy/tools.py
index 4cc529ed1d27bb5c53332fd7829fd3ac9b5c9819..993ae91eaa7fec59e960f168313bb9edf4777657 100644
--- a/sumpy/tools.py
+++ b/sumpy/tools.py
@@ -104,7 +104,7 @@ def mi_power(vector, mi, evaluate=True):
class MiDerivativeTaker(object):
- def __init__(self, expr, var_list, rscale=1):
+ def __init__(self, expr, var_list, rscale=1, sac=None):
r"""
A class to take scaled derivatives of the symbolic expression
expr w.r.t. variables var_list and the scaling parameter rscale.
@@ -175,6 +175,7 @@ class MiDerivativeTaker(object):
empty_mi = (0,) * len(var_list)
self.cache_by_mi = {empty_mi: expr}
self.rscale = rscale
+ self.sac = sac
def mi_dist(self, a, b):
return np.array(a, dtype=int) - np.array(b, dtype=int)
@@ -207,13 +208,21 @@ class MiDerivativeTaker(object):
if (np.array(mi) >= np.array(other_mi)).all()),
key=lambda other_mi: sum(self.mi_dist(mi, other_mi)))
+ def add_to_sac(self, expr):
+ import sumpy.symbolic as sym
+ if self.sac is not None:
+ return sym.Symbol(self.sac.assign_unique("temp", expr))
+ else:
+ return expr
+
class LaplaceDerivativeTaker(MiDerivativeTaker):
- def __init__(self, expr, var_list, rscale=1):
- super(LaplaceDerivativeTaker, self).__init__(expr, var_list, rscale)
- self.r = sym.sqrt(sum(v**2 for v in var_list))
- self.scaled_r = sym.sqrt(sum((v/rscale)**2 for v in var_list))
+ def __init__(self, expr, var_list, rscale=1, sac=None):
+ super(LaplaceDerivativeTaker, self).__init__(expr, var_list, rscale, sac)
+ self.scaled_var_list = [self.add_to_sac(v/rscale) for v in var_list]
+ self.scaled_r = self.add_to_sac(
+ sym.sqrt(sum(v**2 for v in self.scaled_var_list)))
def diff(self, mi):
# Return zero for negative values. Makes the algorithm readable.
@@ -235,22 +244,24 @@ class LaplaceDerivativeTaker(MiDerivativeTaker):
for i in range(dim):
mi_minus_one = list(mi)
mi_minus_one[i] -= 1
+ mi_minus_one = tuple(mi_minus_one)
mi_minus_two = list(mi)
mi_minus_two[i] -= 2
- x = self.var_list[i]
+ mi_minus_two = tuple(mi_minus_two)
+ x = self.scaled_var_list[i]
n = mi[i]
if i == d:
if dim == 3:
- expr -= (2*n-1)*(x/self.rscale)*self.diff(tuple(mi_minus_one))
- expr -= (n-1)**2*self.diff(tuple(mi_minus_two))
+ expr -= (2*n - 1) * x * self.diff(mi_minus_one)
+ expr -= (n - 1)**2 * self.diff(mi_minus_two)
else:
- expr -= 2*(x/self.rscale)*(n-1)*self.diff(tuple(mi_minus_one))
- expr -= (n-1)*(n-2)*self.diff(tuple(mi_minus_two))
+ expr -= 2 * x * (n - 1) * self.diff(mi_minus_one)
+ expr -= (n - 1) * (n - 2) * self.diff(mi_minus_two)
if n == 2 and sum(mi) == 2:
expr += 1
else:
- expr -= 2*n*(x/self.rscale)*self.diff(tuple(mi_minus_one))
- expr -= n*(n-1)*self.diff(tuple(mi_minus_two))
+ expr -= 2 * n * x * self.diff(mi_minus_one)
+ expr -= n * (n - 1) * self.diff(mi_minus_two)
expr /= self.scaled_r**2
self.cache_by_mi[mi] = expr
return expr
diff --git a/test/test_kernels.py b/test/test_kernels.py
index f37e51c669285d7c0500ac82f89beb30f0ad47e8..4e445888e9b7f24cf939fa7f34e27286cb60f2f2 100644
--- a/test/test_kernels.py
+++ b/test/test_kernels.py
@@ -366,7 +366,7 @@ def _m2l_translate_simple(tgt_expansion, src_expansion, src_coeff_exprs, src_rsc
#
# To get the local expansion coefficients, we take derivatives of
# the multipole expansion.
- taker = src_expansion.get_kernel_derivative_taker(dvec, src_rscale)
+ taker = src_expansion.get_kernel_derivative_taker(dvec, src_rscale, sac=None)
from sumpy.tools import add_mi