Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Straight line sin wave plot.

  1. Apr 15, 2005 #1
    What would you call the scale on the Y axis that would plot a sine or cosine wave as a straight lined saw tooth pattern?

    Is such a graphing style in use and does it have a name?
  2. jcsd
  3. Apr 16, 2005 #2
    The type of plot to which you are refering is called a Triangular Wave... has your instructor(s) talked about Fourier anaylsis?
  4. Apr 18, 2005 #3
    The type of plot to which you are refering is called a Triangular Wave... has your instructor(s) talked about anaylsis?[/QUOTE]

    I can see where Triangular Wave is a good description of what a saw tooth pattern looks like, (of course it's not really a Triangular Wave we are talking about a sine wave here). But did your instructor(s) give a name to the Vertical Scale against the 'angular' Horizontal Scale that causes a Sine Wave plotted with it to appear as a Triangular Wave? Or a name to the type of graph or plot this would be called?

    Your not calling it a Fourier Graph or Fourier Plot are you?

    I'm only assuming, but it seems to me it would only valid from -1 to +1, that is it would not be "scalable" for use with larger numbers (as a log graph is). Rather the data would need to be scaled to a max of 1.

  5. Apr 18, 2005 #4
    I've never heard of this type of scale, so I can't give you a name.

    You are referring to [tex]y_{scaled}=\sin^{-1}{y_{real}}[/tex], correct?

    Yes, in that case, it could not directly be expanded to y>1.
  6. Apr 18, 2005 #5
    I know what your talking about, we looked at those kind of waves in E&M when doing voltage analysis in lab. The instructor called them triangle waves.
  7. Apr 18, 2005 #6

    I'll keep looking a bit but I'm guessing I'll have to create my own.
    I'm thinking it would be helpful in ploting and comparing statistical results involving sin functions.
  8. Apr 21, 2005 #7
    I don't know if you're this far, but even using Matlab or Mathematica will allow you to make use of the following Fourier series for the triangular wave.


    Where A of course is referring to the amplitude.
  9. Apr 22, 2005 #8
    NO - I believe what your describing is a near infinite number of frequencies or waves to produce a triangular wave (Same kind of thing required for a square wave).

    What I have is one wave of only one frequency. I’m just plotting it so that the PLOT is triangular by finding the appropriate Y axis scale.
    Thus a Triangular plot here is not the same as a triangular wave.
  10. Apr 22, 2005 #9
    There seems to be a lot of confusion here, so hopefully to clear things up:

    He's not talking about infinitely many sine waves being added to make a triangle wave, he is asking about changing the scale of the y-axis to make a single sine wave appear to be a triangular wave. This is analogous to the way a log plot makes an exponential graph appear linear.
  11. Apr 22, 2005 #10
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook