Re: Can anyone help me fix my circle math?

["Chris Cheatham" <chris@xxxxxxxxxxxxxxxxxx>]

Thanks everyone. You guys never cease to amaze me. Between what has been
posted and what I have received privately, I believe I see a way to do this
correctly now. Requires quite a rewrite  to draw every bar vs. at the end of
the circle, but that is the best way to do it. Quite a pesky problem,
concentric circles at sqrt 2 increments within a fixed square, so not neat
even bar radii.

Thanks again,
Chris
----- Original Message ----- 
From: "Bob Fulks" <bfulks@xxxxxxxxxxxx>
To: "Chris Cheatham" <chris@xxxxxxxxxxxxxxxxxx>; "Omega List"
<omega-list@xxxxxxxxxx>
Cc: "Gary Fritz" <fritz@xxxxxxxx>
Sent: Sunday, February 13, 2005 4:45 PM
Subject: Re: Can anyone help me fix my circle math?


> You guys are making this harder than it should be. :-)
>
>
> In the attached figure (Omega.08) - for a circle we know:
>
>    R^2 = a^2 + y^2
>
> so: y = SQRT(R^2 -a^2)
>
> Since: a + b = R
>
> then:  a = b - R
>
> so: y = SQRT(R^2 - a^2)
>       = SQRT(R^2 - (b - R)^2)
>       = SQRT(R^2 - b^2 + 2*b*R - R^2)
>       = SQRT(    - b^2 + 2*b*R      )
>       = SQRT( 2*b*R - b^2)
>
>       = SQRT( b * (2*R - b))
>
>
> This gives us the height as a function of the horizontal distance "b"
>
> To translate this into TradeStation code:
>
> Let: b = CurrentBar - cpBar - R
>
> where: cpBar is the bar number of the center point.
>
> Add a scale factor to adjust the price scale and you get the code below.
>
> The second picture Omega.09 shows the circle. Inside it is a circle drawn
with the TradeStation drawing tools. They look pretty similar to me...
>
> Bob Fulks
>
> -----------------------------------------------------
>
> Input: R(50), cpBar(250), cpPrice(1200), ScaleFac(1.0);
>
> Var: b(0), y(0);
>
> b = CurrentBar - cpBar + R;
>
> if b >= 0 and b <= 2 * R then begin
>    y = ScaleFac * SquareRoot(b * (2 * R - b));
>    Plot1(cpPrice + y, "Upper");
>    Plot2(cpPrice - y, "Lower");
> end;
>
> ------------------------------------------------------
>