I can't find the definition of a function $f(x); x \in [-1;1]$ where $(x|f(x))$ is a point on the unit-circle.
Can you please give me a hint?
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Background:
I want to render a filled circle (programatically) onto a screen using an iteration from $x-rad \rightarrow x+rad$ where $x$ is the x-position of the circle on the screen, and $rad$ is the radius.
Solution:
$f(x) = cos(sin^{-1}(x))$
seems to work pretty well. For the programmers under us, here is Python-code to demonstrate my approach:
import math def drawCircle(xpos, ypos, radius): for x in xrange(radius * 2): x = x - radius ytop = math.cos(math.asin( x / radius )) ybot = -ytop x = x + xpos drawLine( x, ypos+ytop, x, ypos+ybot)
Result: