(Formerly numbered 171.) (Same as Atmospheric and Oceanic Sciences M171.) Lecture, four hours. Requisites: course M71, Mathematics 3A, 3B, and 3C (or 31A and 31B). Misfit modeling and quantitative comparisons of acquired data sets and theory. Forward modeling from fundamental equations. Examples, experiments, and exercises from disciplines within geosciences. P/NP or letter grading.