From 7cf3197b8378fa16739f3c740bd80e9ead04765d Mon Sep 17 00:00:00 2001
From: Isuru Fernando <isuruf@gmail.com>
Date: Tue, 20 Aug 2019 08:59:57 -0500
Subject: [PATCH] Fix biharmonic kernel expressions
---
sumpy/kernel.py | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/sumpy/kernel.py b/sumpy/kernel.py
index 99222f68..aebaa9fe 100644
--- a/sumpy/kernel.py
+++ b/sumpy/kernel.py
@@ -431,13 +431,14 @@ class BiharmonicKernel(ExpressionKernel):
init_arg_names = ("dim",)
def __init__(self, dim=None):
+ # See https://arxiv.org/abs/1202.1811
r = pymbolic_real_norm_2(make_sym_vector("d", dim))
if dim == 2:
- expr = r**2 * var("log")(r)
- scaling = 1/(8*var("pi"))
+ expr = r**2 * (var("log")(r) - 1)
+ scaling = -1/(8*var("pi"))
elif dim == 3:
expr = r
- scaling = 1 # FIXME: Unknown
+ scaling = 1/(8*var("pi"))
else:
raise RuntimeError("unsupported dimensionality")
--
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