Complex analysis handwritten Notes
Complex analysis handwritten Notes-2
Complex analysis notes for b.sc ,M.sc, and engineering students
The study of complex analysis is important for students in engineering and the physical sciences and is a central subject in mathematics. In addition to being mathematically elegant, complex analysis provides powerful tools for solving problems that are either very difficult or virtually impossible to solve in any other way.
Complex analysis is the branch of mathematics investigating holomorphic functions, i.e. functions which are defined in some region of the complex plane, take complex values, and are differentiable as complex functions. Complex differentiability has much stronger consequences than usual (real) differentiability. For instance, every holomorphic function is representable as power series in every open disc in its domain of definition, and is therefore analytic. In particular, holomorphic functions are infinitely differentiable, a fact that is far from true for real differentiable functions. Most elementary functions, such as all polynomials, the exponential function, and the trigonometric functions, are holomorphic. See also : holomorphic sheaves and vector bundles.
Analytic concepts such as limits, derivatives, integrals, and infinite series (all explained in the sections Technical preliminaries and Calculus) are based upon algebraic ideas, together with error estimates that define the limiting process: certain numbers must be arbitrarily well approximated by particular algebraic expressions. In order to represent the concept of an approximation, all that is needed is a well-defined way to measure how “small” a number is. For real numbers this is achieved by using the absolute value |x|. Geometrically, it is the distance along the real number line between x and the origin 0. Distances also make sense in the complex plane, and they can be calculated, using Pythagoras’s theorem from elementary geometry (the square of the hypotenuse of a right triangle is equal to the sum of the squares of its two sides), by constructing a right triangle such that its hypotenuse spans the distance between two points and its sides are drawn parallel to the coordinate axes.