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Shelnutt2
08-05-07, 05:19 PM
OK I can't seem to graph the sine functions correctly.

Take a look here (http://freespace.virgin.net/hugo.elias/models/m_perlin.htm). The 6 example sine functions and then the sine function thats all 6 added together. I can't seem to get those to graph out on my TI-84.

I have the six sine functions as below.
Y=128*sine(x/4)
Y=64*sine(x/8)
Y=32*sine(x/16)
Y=16*sine(x/32)
Y=8*sine(x/64)
Y=4*sine(x/128)

When I graph those functions they just look like clean waves, no deviations like what is on the website. My graphs just looks like a sine wave.. What am I doing wrong? Is my TI-84 not able to graph it correctly?

Thanks!

Roofles
08-05-07, 05:51 PM

Check to make sure you have the correct scaling on your graph. You might be clipping some of the waves.

Trombe
08-05-07, 07:12 PM
Not sure what you were expecting?

http://i56.photobucket.com/albums/g185/Trombe29/graphprove.jpg

Mortis03
08-05-07, 11:19 PM
So are you wanting to graph a noisy wave? Don't get exactly what you are trying to do.

The 6 graphs of the noise functions aren't exactly sine waves either. Yeah, they resemble one, but they look a whole lot more complex then just a simple y=asin(x/f)

Frodo Baggins
08-05-07, 11:38 PM
OK I can't seem to graph the sine functions correctly.

Take a look here (http://freespace.virgin.net/hugo.elias/models/m_perlin.htm). The 6 example sine functions and then the sine function thats all 6 added together. I can't seem to get those to graph out on my TI-84.

I have the six sine functions as below.
Y=128*sine(x/4)
Y=64*sine(x/8)
Y=32*sine(x/16)
Y=16*sine(x/32)
Y=8*sine(x/64)
Y=4*sine(x/128)

When I graph those functions they just look like clean waves, no deviations like what is on the website. My graphs just looks like a sine wave.. What am I doing wrong? Is my TI-84 not able to graph it correctly?

Thanks!

Well, for one thing, there's no "e" in the mathematical notation of "sin".

You're not very clear on what is it you want to do. Are you trying to create a "noise function" by adding together sinusoidals of various frequencies and amplitude? In that case, simply inputting in y = y1 + .. + y6 should give you something 'random'.

http://img530.imageshack.us/img530/8550/mathsineux1.th.gif (http://img530.imageshack.us/my.php?image=mathsineux1.gif)

Shelnutt2
08-05-07, 11:42 PM
ok, yeah I was confused. I miss interpreted the website, and I thought it was saying you get a noise wave/function by adding sin functions together. Seemed odd, but since they had graphs of it, I was trying to figure out what I was doing wrong.

So yeah sin waves != noise wave. You use a random number generator to create a noise function.

Sorry for the confusion.

Frodo Baggins
08-05-07, 11:54 PM
ok, yeah I was confused. I miss interpreted the website, and I thought it was saying you get a noise wave/function by adding sin functions together. Seemed odd, but since they had graphs of it, I was trying to figure out what I was doing wrong.

So yeah sin waves != noise wave. You use a random number generator to create a noise function.

Sorry for the confusion.

No, you correctly interpreted the website. You can get a "noisy" function by adding together sinusoidals. You just have to be more selective in the way you choose them. (Or you have to add together more of them). It also very much depends on your "point of view".

For example, try graphing sin(1/x) from say, x = 0.001 to x = 0.01.

From far away, there is no way you can predict that. But from close up, it's definitely sinusoidal.