О книге
This lecture introduces functions of several variables, explaining the roles of independent and dependent variables, domain, and range. It covers methods for visualizing such functions, including graphs in three-dimensional space and level lines on a plane. The core topic is the limit of a function of two variables. For a limit to exist, it must be the same regardless of the path taken to approach the point. Examples demonstrate how different curves can yield different limit values, proving that a limit does not exist. The relationship between double and iterated limits is also discussed. Finally, the lecture addresses continuity, defining when a function is continuous at a point and classifying discontinuities. It concludes with the Weierstrass and Cauchy theorems, explaining why properties like closedness and connectedness are essential for continuous functions on sets.
