Updated the Makefile to regenerate some of the pictures.

doc/hpcs2011_tutorial/Makefile

-all:
+all: presentation.pdf
+
+presentation.pdf: presentation.tex pics/f_optimized.png pics/logreg_pydotprint_prediction.png
+# pics/f_unoptimized.png pics/logreg_pydotprint_predic.png pics/logreg_pydotprint_train.png
 	pdflatex presentation.tex
+
+pics/f_optimized.png: simple_example.py
+	python simple_example.py
+
+pics/logreg_pydotprint_prediction.png: logreg_example.py
+	python logreg_example.py
+#pics/f_unoptimized.png: simple_example.py
+#	python simple_example.py
+