Table of contents : Front Matter....Pages i-xxx Preliminary Considerations....Pages 1-43 Equations of Elliptic Type....Pages 44-102 Equations of Parabolic Type....Pages 103-146 Equations of Hyperbolic Type....Pages 147-182 Some Generalizations....Pages 183-211 The Method of Finite Differences....Pages 212-307 Back Matter....Pages 309-322