To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The complex exponential function exp(z), sin(z), cos(z) are defined as power series, used to prove properties analogous to the real case, with new ideas such as Euler's formula exp(z) = cos(z) + i.sin(z). Defining e = exp(1) gives exp(z) = e^z. For z= x + iy, e^z= e^(x + iy) = e^x.e^(iy) = e^x(cos(y) + i sin(y)). Real properties of the exponential and the trigonometric functions are used to build the complex generalisations, linking symbolic properties to visual dynamic complex representations. These include the periodicity of exp, sine and cosine and introduction of other complex trigonometric and hyperbolic functions.
Derivative of a complex function defined by analogy with the real case, shown to satisfy corresponding rules for combinations of functions. Differentiable paths. Power series are differentiable an infinite number of times in their circle of convergence unlike real functions which may be differentiable a certain number of times but not more. Examples are given of the 'bad behaviour' of real functions contrasting with the infinite differentiability of complex functions in an open connected domain.
Radians, the argument arg(z) is deduced using real power series. The winding number of a path round a point in terms of a continuous choice of argument. Using the paving lemma. Calculation as an integral. Components of the complement of a closed path.
Looks at simple properties of plane topology, including open and closed sets, limits and continuity. Paths are continuous maps from a real interval to the complex plane. A subset S of the plane is (path-) connected if any two points in S can be connected by a path in S. A domain is an open connected subset. To simplify proofs, the Paving Lemma is proved, showing that a path in a domain D can be covered by a finite number of discs so that any two points within D can be joined by a step-path in D consisting of horizontal and vertical steps. This allows visual ideas of continuous paths to be interpreted using only horizontal and vertical steps, linking intuition in the complex plane to the real case.