commit a2b99df9e7008ae9c31caa0c6b9eebc6e41ecd55
Author: John Denker <jsd@av8n.com>
Date:   Wed Jan 21 13:17:22 2015 -0700

    add some automatic dependency checking

diff --git a/src/Makefile b/src/Makefile
index 8c6da46..ebcd37e 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -38,6 +38,15 @@ APPS = test1 test2 test3 test4 test5 test6 test-dipole \
 	test14 test16 ivis sectors otree wb1 test17 chargedist test18 test19 wb2 test20 \
 	test21 test22 test23 test24 test25 wb3 #polywell_double tt tt3 #tt2 #tt # tt
 
+## dependency-finding scheme (with local mods) based on:
+## http://www.gnu.org/manual/make-3.77/html_mono/make.html#SEC42
+## (requires an include statement at end of the makefile)
+
+%.d: %.cpp
+	@$(SHELL) -ec '$(CXX) -MM $(CXXFLAGS) $< \
+		| sed '\''s/\($*\)\.o[ :]*/\1.o $@ : /g'\'' > $@; \
+		[ -s $@ ] || rm -f $@'
+
 ifeq ($(PNG),yes)
   LDFLAGS += -lpng
   CXXFLAGS += -DENABLE_PNG
@@ -292,3 +301,6 @@ ephi_wrap.o: ephi.swig libephi.a
 	$(CXX) -I/usr/include/python -c $(CXXFLAGS) ephi_wrap.cxx
 
 -include .depend
+
+include $(APPS:%=%.d)
+include $(OBJS:%.o=%.d)