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Number of possible combinations of...

  1. Jun 30, 2015 #1
    How do I find all the different combinations of the point (x,y,z) when x,y, and z can be either positive and negative? For example, what I'm trying to solve is (+,+,+), (+,+,-), (+,-,-), etc. How do I find out how many different points there are and the sign of each variable for each distinct point?
     
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  3. Jun 30, 2015 #2

    phinds

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    In 3D coordinates, how many "quadrants" are there?
     
  4. Jun 30, 2015 #3
    There are eight octants. I'm not sure about quadrants.


    EDIT: OK, I understand now. Thank you.
     
    Last edited: Jun 30, 2015
  5. Jun 30, 2015 #4

    phinds

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    Right. So how many ways could you have the point positioned, from the point of view of differing signs?
     
  6. Jul 1, 2015 #5

    HallsofIvy

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    As the names imply, in two dimensions there are four "quadrants" and in three dimensions there are eight "octants. In n dimensions there are [itex]2^n[/itex] such subsets.
     
  7. Jul 1, 2015 #6

    phinds

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    Yeah, that's why I put "quadrants" in quotes, to mean just "sections", which you more appropriately identified as octants.
     
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