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: Reading Mathematical Symbols

  1. Dec 23, 2013 #1
    I am not too used to reading mathematical text using symbols. I need some help confirming what I have in my textbook.

    The book is describing a point in 3D space using the definition

    R x R x R = {(x,y,z) | x,y,z [itex]\in[/itex] R} and R is all real numbers

    Using this source describing the definition of each symbol: http://en.wikipedia.org/wiki/List_of_mathematical_symbols

    I came up with this definition in words

    The Cartesian product of R and R and R is equal to the set consisting of (x,y,z) such that x,y,z are elements of R.

    Is this an accurate definition in words? I'm finding that being able to read the precise definition from math symbols is becoming even more important as my courses continue. Any other input on reading math symbols is appreciated and encouraged.
  2. jcsd
  3. Dec 23, 2013 #2
    You're right in that you need to be able to learn what mathematical symbols mean as a way to determine shorthand. It's very important in set theory (and real analysis, which is a total pain but appreciable nevertheless).

    Your definition states that "The Cartesian product of R, R, and R is equal to a set of three real numbers x, y, and z". That just describes 3D space really... 3D space is R^3, or the set of all real numbers in three dimensions. By setting x, y, and z separately equal to a real number and creating a vector space that consists of all possible linear combinations of x, y, and z, we span out all of 3D space (or R^3). Your book likes to use some technical jargon instead of linear algebra, which makes more sense intuitively from a non-mathematical standpoint.
  4. Dec 23, 2013 #3
    Okay, thank you. The textbook goes on from their definition to say "We have given a one-to-one correspondence between points P in space and ordered triples (a,b,c) in R^3".

    I think I understand this statement to be the Point P is located at (a,b,c). Is this also a fair comprehension?
  5. Dec 24, 2013 #4


    User Avatar
    Science Advisor

    Not quite, because it is not talking about a single point, P. What it is saying is that every point in 3 dimensional space can be associated with a triple of numbers.
  6. Dec 24, 2013 #5
    Indeed, HallsofIvy is correct. The book is talking about the set of all points in 3D space and how one can associate ordered triples of the form (a,b,c) with each such point. The book's statement also implies that these points (a,b,c) are unique in describing a single location in 3D space (hence a one-to-one correspondence).
  7. Dec 24, 2013 #6
    Thank you! After reading a second time, I noticed it said "points", plural, and that lines up with the explanation. Thanks for helping me.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted