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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?
    RB
     
  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.

    RB
     
  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
    Yes

    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.
    RB
     
  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.

    [tex]f(t)={\frac{8A}{\pi^2}}\sum_{n=1,3,5,...}^{\infty}[\frac{1}{n^2}sin(\frac{n\pi}{2})]sin(n{\omega_0}t)[/tex]

    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
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