Maths - Trig Graphs

[Choppa]

I was going well with this spell, I want to make it move in a cosine wave and I was wondering if this equation can be done in radians...

y = cos(x - 2)

Do I have to convert the 2 into something else first?

 

[Ghan]

Well, in radians, 360 degrees becomes 2*PI.
So, if you want to convert to radians, multiply by PI then divide by 180.
Do the reverse to convert to degrees.

Now, you can use 2 there, but it will actually subtract about 115 degrees.

I guess I don't really know what you're asking....

 

[Sim]

What will "x" be?

A real number between -1 and 1? 500?

 

[Choppa]

Ok so how would I normaly go about doing

y = cos(x - #)             radians

Because I know that if it was #pi it would effect the frequency, and if it wasn't in brackets it would be the y placement but i'm stuck on this, and I can't seem to figure out what exactly I need to do.

 

[Ghan]

> I can't seem to figure out what exactly I need to do.

I don't know what you want it to do.

What is it that you want to happen that is different from a regular sine wave?

 

[Sim]

It depends on what x is.

Show us your trigger.

BTW:

> I was wondering if this equation can be done in radians...

native Cos      takes real radians returns real

radians

Alternatively, CosBJ takes real degrees.

 

[Ghan]

> It depends on what x is.

Eh?
It's not inverse, remember.

X can be any real number....

I don't really know what you want with the (x - z) part....
Are you two on a different level than I?
I'm kind of confused.

 

[Choppa]

I don't really know what you want with the (x - z) part....

It's x minus two.

All I really want to know is how the - 2 in brackets effects the wave, does it move it vertically or horizontally and if so by how much?

 

[MoonSlinger]

Trigonometry: Factors that affect how a Cos Curve look

On a simple 2D with x, y axis
Equation: y = ACos(Bx + C)

A - affects the maximum value of y (how high the graph will go)
B - determines how many "waves" will appear in a range of 360 deg of x
C - cause a horizontal shift. a positive number shifts the graph right

Note: Deg / Radians are just like inches to cm, its just conversion using a constant.

These are ancient stuffs for me, so correct me if I am wrong.

 

[Choppa]

Yeah that looks right, and for C horizontal shift, for my equation
y = cos(x - 2)
How far am I supposed to shift it to the right?
Because this is in radians.

 

[Sim]

> does it move it vertically or horizontally and if so by how much?

Horizontally.

 

[Foresector]

Umm, I'm not too sure about that..

I thought Y=Cos(x-2) would make the graph shift downwards.. I might be wrong though

EDIT: Sorry its horizontal,

 

[Chjoodge]

B - determines how many "waves" will appear in a range of 360 deg of x

Yes, but inversely: there will be 1/B waves. Higher B results in less waves.

C - cause a horizontal shift. a positive number shifts the graph right

Inversly - left.

All I really want to know is how the - 2 in brackets effects the wave, does it move it vertically or horizontally and if so by how much?

If you ask how the -2 affects the given unit's movement, the effect of that -2 is that it will make the unit start its move on a different point of the wave. I guess this is not what you want.

If you could describe what you're aiming for, we could probably help you get the formula you need.

 

[Choppa]

Ok pretend i'm not talking about warcraft, let's say i'm just talking about maths.

y = cos(x - 2)

What would this wave look like, I know it'd look like a cosine graph with an amplitude of 1, but where would you start to draw the wave, and how do you know how far along the graph would you move the wave. (x of graph is radians)

 

[Chjoodge]

You would move the wave 2 units to the right, "units" being radians in your case. See the attached image.

 

[Choppa]

How did you know how far a unit was along?

 

[Chjoodge]

Pi is 3,14, so '2' is in about two-thirds between zero and Pi, if that's what you mean.