1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Mapping question I don't understand

  1. Dec 5, 2013 #1
    Hi I uploaded the question and its answer first of all I am not good at all in mapping I don't understand it that much like here we want the output of the function under that specific domain that's what we want to see.
    I understand until PI < alpha < 5/2 * PI but I don't understand how did he get
    f(D) = {|z| < 2 , -PI < Arg(z) < PI/2} I don't get that could someone please explain because I need to understand this.

    Attached Files:

  2. jcsd
  3. Dec 5, 2013 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If you take the range ##\pi < \alpha <\frac 5 2 \pi##, you can subtract ##2\pi## from the ##\pi## and ##\frac 5 2 \pi## and it is the same region in the plane. So ##-\pi < \alpha < \frac \pi 2## describes the same region.
  4. Dec 5, 2013 #3
    Oh I see that makes alot of sense thank you !!!!
  5. Dec 5, 2013 #4
    could you please also like explain maybe more about this question about how did he arrive to this solution coz I am not sure that my understanding is correct or intuition is right..
  6. Dec 5, 2013 #5


    Staff: Mentor

    Which part don't you understand?
  7. Dec 6, 2013 #6
    So I was wondering how do we systematically solve stuff like this ? are we looking for how some function output under certain set of conditions ? like for example f(x) = x^2 and we restrict the domain to be something like
    [0,2] and see what is the range of output we are trying to get ?? I don't really understand what's going on here I just know how to solve in some scenrios but I don't get are we actually doing ...
  8. Dec 7, 2013 #7
    Is there systematic way to do these kind of problems?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted