Complex function of several variables

Click For Summary
The discussion focuses on the definition of continuity for complex functions of several variables, specifically how it applies to a complex-valued function F defined on a subset of C^n. Continuity at a point x in A is established similarly to continuity in any metric space, with the metric defined as the distance between points in C^n. Participants express difficulty finding comprehensive resources that cover foundational topics like continuity and limits in higher-dimensional complex analysis. Recommendations for books that address these basic concepts are sought. Additionally, it is confirmed that the Heine-Borel theorem holds in complex Euclidean space, meaning a subset is compact if it is closed and bounded.
gotjrgkr
Messages
84
Reaction score
0
Hi!

While studying Global Cauchy Theorems in complex analysis, I've realized that I need to know a definition of continuity of a complex function of several variables...
Thus, I ask you the definition of continuity of a complex function of several complex variables.
What I mean is ... ; Given a complex valued function F of several complex variables(F:A\rightarrowC where A is a subset of C^{n} for a positive integer n and C implies the complex plane), What does it mean F is continuous at a point x in A for this function??

In addition, I also ask you whether the definition of metric of a point x=(z_{1},...,z_{n}) in the comples euclidean space C^{n} is just \sqrt{\sum^{n}_{i=1}\left|z_{i}\right|^{2}} or not??
 
Physics news on Phys.org
Yes, it's a metric space. So the definition of continuity is the same as in any metric space. But a metric is the distance between two points x=(z_1,...,z_n) and x'=(z'_1,...,z'_n) and that would be d(x,x')=\sqrt{\sum^{n}_{i=1}\left|z_{i}-z'_{i}\right|^{2}}.
 
Dick said:
Yes, it's a metric space. So the definition of continuity is the same as in any metric space. But a metric is the distance between two points x=(z_1,...,z_n) and x'=(z'_1,...,z'_n) and that would be d(x,x')=\sqrt{\sum^{n}_{i=1}\left|z_{i}-z'_{i}\right|^{2}}.

Oh,, I see...
I also wanted to get such an answer for my question.
1. But, I couldn't find any book dealing with a complex function of several variables.
Of course, there's a book dealing with such a kind of field. But, it seems that almost every book omit the basic part of it such as continuity, limit, and topology related with higer dimensional complex metric space... So, could you recommend a book explaining such basic parts of the complex function of several variables ( basic concepts such as continuity, definition of metric of the space, limit, etc).
I know this is a quite a different question for the main question, but
2. I also want to ask you if in the complex euclidean space(considered as a metric space as you show) Heine-Borel Theorem still holds or not(I mean that a subset is compact in the metric space iff the subset is closed and bounded in the metric space)...
 
gotjrgkr said:
2. I also want to ask you if in the complex euclidean space(considered as a metric space as you show) Heine-Borel Theorem still holds or not(I mean that a subset is compact in the metric space iff the subset is closed and bounded in the metric space)...

Yes. \mathbb{C} is isomorphic with \mathbb{R}^2 and the Heine-Borel theorem holds in \mathbb{R}^2.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

Similar threads

  • · Replies 27 ·
Replies
27
Views
2K
Replies
7
Views
2K
  • · Replies 17 ·
Replies
17
Views
3K
Replies
8
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
Replies
4
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K