From 59c66f44c69f47c9c3545cdb9c7546f9e3f0b619 Mon Sep 17 00:00:00 2001
From: Christoph Lehner <christoph@lhnr.de>
Date: Sat, 15 Jun 2024 15:58:59 +0200
Subject: [PATCH] checkerboard ui

---
 lib/gpt/core/checkerboard.py |  8 +++++++-
 tests/core/core.py           | 15 +++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lib/gpt/core/checkerboard.py b/lib/gpt/core/checkerboard.py
index 7762c12cf..d8775e6b5 100644
--- a/lib/gpt/core/checkerboard.py
+++ b/lib/gpt/core/checkerboard.py
@@ -53,7 +53,13 @@ def str_to_cb(s):
         assert 0
 
 
-def pick_checkerboard(cb, dst, src):
+def pick_checkerboard(cb, dst, src = None):
+    if src is None:
+        src = dst
+        dst = gpt.lattice(src.grid.checkerboarded(gpt.redblack), src.otype)
+        pick_checkerboard(cb, dst, src)
+        return dst
+        
     assert len(src.v_obj) == len(dst.v_obj)
     for i in src.otype.v_idx:
         cgpt.lattice_pick_checkerboard(cb.tag, src.v_obj[i], dst.v_obj[i])
diff --git a/tests/core/core.py b/tests/core/core.py
index 7fb4e1f6b..427d5fb8e 100755
--- a/tests/core/core.py
+++ b/tests/core/core.py
@@ -487,7 +487,22 @@ def correlate_test_4d(a, b, x):
     g.message(f"Test sparse slice: {eps}")
     assert eps < l.grid.precision.eps * 1e3
 
+################################################################################
+# Test checkerboard
+################################################################################
+a = a[0]
+b = b[0]
+a_even = g.pick_checkerboard(g.even, a)
+a_odd = g.pick_checkerboard(g.odd, a)
+b[:] = 0
+g.set_checkerboard(b, a_even)
+g.set_checkerboard(b, a_odd)
+eps2 = g.norm2(a-b)
+g.message(f"Checkerboard: {eps2}")
+assert eps2 == 0.0
+
 ################################################################################
 # Test mem_report
 ################################################################################
 g.mem_report()
+