OpenEuphoria

Re: trig

• Posted by Lewis Townsend <keroltarr at hotmail.com> Apr 18, 2004
• 628 views

Okay,

Maybe I need to explain myself better:
I have broken up the circle (360 deg) into 16 equal angles; each 22.5 degrees.
I have a sequence of these angles:
{0,22.5,45,67.5,90,112.5,135,157.5,180,202.5,225,247.5,270,292.5,315,337.5}

>From that I have evaluated 16 {x,y} vectors with the following formula:
{ sin (angle), cos (angle) }
The above is simplified for readability; degree/radian conversion is done
separately.
This produces the following sequence <approximately>
{{0,1},{0.383,0.924},{0.707,0.707},{0.924,0.383},{1,0},{0.924,-0.383},{0.707,-0.707},{0.383,-0.924},{0,-1},{-0.383,-0.924},{-0.707,-0.707},{-0.924,-0.383},{-1,0},{-0.924,0.383},{-0.707,0.707},{-0.383,0.924}}

I want to recognize any random {x,y} vector as its closest match in the list.
I can scale any vector to a distance of 1 with the following code:

dir = random_vector --{x,y}
dist = sqrt(power(dir[1],2)+power(dir[2],2))
if dist != 1 then
	dir[1] = dir[1] * 1 / dist
	dir[2] = dir[2] * 1 / dist
end if

The question is how do I find its closest match in either the vector list or the
angle list.
All I need is an element number.