# Straight line sin wave plot.

1. Apr 15, 2005

### RandallB

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. Apr 16, 2005

### Theelectricchild

The type of plot to which you are refering is called a Triangular Wave... has your instructor(s) talked about Fourier anaylsis?

3. Apr 18, 2005

### RandallB

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

4. Apr 18, 2005

### Moo Of Doom

I've never heard of this type of scale, so I can't give you a name.

You are referring to $$y_{scaled}=\sin^{-1}{y_{real}}$$, correct?

Yes, in that case, it could not directly be expanded to y>1.

5. Apr 18, 2005

### whozum

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.

6. Apr 18, 2005

### RandallB

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

7. Apr 21, 2005

### Theelectricchild

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.

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

Where A of course is referring to the amplitude.

8. Apr 22, 2005

### RandallB

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.

9. Apr 22, 2005

### eddo

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.

10. Apr 22, 2005

Explain!!!