bugfix for is_integrated=True sources (#2044)

* bugfix for is_integrated=True sources

* lower tolerance in single precision

* fix is_integrated for CustomSource

python/Makefile.am

@@ -70,6 +70,7 @@ TESTS =                                        \
     $(TEST_DIR)/test_get_epsilon_grid.py       \
     $(TEST_DIR)/test_holey_wvg_bands.py        \
     $(TEST_DIR)/test_holey_wvg_cavity.py       \
+    $(TEST_DIR)/test_integrated_source.py      \
     $(KDOM_TEST)                               \
     $(TEST_DIR)/test_ldos.py                   \
     $(MDPYTEST)                                \

python/source.py

@@ -173,7 +173,7 @@ def __init__(self, frequency=None, start_time=0, end_time=1.0e20, width=0,
         if frequency is None and wavelength is None:
             raise ValueError("Must set either frequency or wavelength in {}.".format(self.__class__.__name__))
 
-        super(ContinuousSource, self).__init__(**kwargs)
+        super(ContinuousSource, self).__init__(is_integrated=is_integrated, **kwargs)
         self.frequency = 1 / wavelength if wavelength else float(frequency)
         self.start_time = start_time
         self.end_time = end_time
@@ -240,7 +240,7 @@ def __init__(self, frequency=None, width=0, fwidth=float('inf'), start_time=0, c
         if frequency is None and wavelength is None:
             raise ValueError("Must set either frequency or wavelength in {}.".format(self.__class__.__name__))
 
-        super(GaussianSource, self).__init__(**kwargs)
+        super(GaussianSource, self).__init__(is_integrated=is_integrated, **kwargs)
         self.frequency = 1 / wavelength if wavelength else float(frequency)
         self.width = max(width, 1 / fwidth)
         self.start_time = start_time
@@ -301,7 +301,7 @@ def __init__(self, src_func, start_time=-1.0e20, end_time=1.0e20, is_integrated=
           automatically determine the decimation factor of the time-series updates
           of the DFT fields monitors (if any).
         """
-        super(CustomSource, self).__init__(**kwargs)
+        super(CustomSource, self).__init__(is_integrated=is_integrated, **kwargs)
         self.src_func = src_func
         self.start_time = start_time
         self.end_time = end_time

python/tests/test_integrated_source.py

@@ -0,0 +1,32 @@
+import unittest
+import meep as mp
+import numpy as np
+
+# Test that is_integrated=True source correctly generates planewaves
+# for sources extending into the PML, as in this tutorial:
+#      https://meep.readthedocs.io/en/latest/Perfectly_Matched_Layer/#planewave-sources-extending-into-pml
+# Regression test for issue #2043.
+
+class TestIntegratedSource(unittest.TestCase):
+
+    def test_integrated_source(self):
+        sources = [mp.Source(mp.ContinuousSource(1,is_integrated=True),
+                            center=mp.Vector3(-2),
+                            size=mp.Vector3(y=6),
+                            component=mp.Ez)]
+        sim = mp.Simulation(resolution=20,
+                            cell_size=(6,6),
+                            boundary_layers=[mp.PML(thickness=1)],
+                            sources=sources,
+                            k_point=mp.Vector3())
+        sim.run(until=30)
+
+        # field in mid-plane should be nearly constant,
+        # so compute its normalized std. dev. and check << 1
+        ez = sim.get_array(mp.Ez, center=mp.Vector3(2), size=mp.Vector3(y=6))
+        std = np.std(ez) / np.sqrt(np.mean(ez**2))
+        print("std = ", std)
+        self.assertAlmostEqual(std, 0.0, places = 4 if mp.is_single_precision() else 8)
+
+if __name__ == '__main__':
+    unittest.main()