Patch Set 1: gain familiarity with unit tests... added simple
4x4 subtract test
Patch Set 2: fixed mistakes, parameterized as suggested
Patch Set 3: randomized the source/predictor data
Change-Id: I33432bdf7c9f2a9b8c2533a37106382c2a8209ee
Signed-off-by: Scott LaVarnway <slavarnway@google.com>