Add ability to generate plots from scripts

.gitignore

@@ -1,2 +1,7 @@
 build_html/*
 build_ipynb/*
+figures/generated/*
+.matplotlib/*.cache
+*~
+\#*
+.ipynb_checkpoints

.matplotlib/matplotlibrc

@@ -0,0 +1,2 @@
+backend : Template
+

Makefile

@@ -9,6 +9,7 @@ VPATH = markdown
 #     intermediate IPython notebooks.
 BUILD_HTML = build_html
 BUILD_NB = build_ipynb
+FIGURES = figures/generated
 
 # TITLES: This should be an exhaustive list of all the chapters to be
 #     built, and correspond to markdown filenames in the markdown
@@ -21,6 +22,11 @@ TITLES := preface ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8 epilogue
 CHS_ := $(addprefix $(BUILD_HTML)/,$(TITLES))
 chs: build_dirs $(addsuffix .html,$(CHS_))
 
+ch3: $(FIGURES)/radar_time_signals.png
+
+$(FIGURES)/%.png: script/%.py $(FIGURES)
+	MPLCONFIGDIR=./.matplotlib python $< $@
+
 # %.html: How to build an HTML file from its corresponding IPython
 #     notebook.
 $(BUILD_HTML)/%.html: $(BUILD_NB)/%.ipynb
@@ -46,6 +52,8 @@ $(BUILD_HTML):
 	 mkdir -p $(BUILD_HTML)
 $(BUILD_NB):
 	 mkdir -p $(BUILD_NB)
+$(FIGURES):
+	 mkdir -p $(FIGURES)
 
 # all: build the book.
 all: chs
@@ -56,3 +64,4 @@ clean:
 
 clobber: clean
 	 rm -rf $(BUILD_HTML)
+	 rm -rf $(FIGURES)