[PD] Graph a circle arc in an array?

Mathieu Bouchard matju at artengine.ca
Sun Apr 10 17:52:26 CEST 2011


On Sun, 10 Apr 2011, Tyler Leavitt wrote:

> I've not had any real success using the formulas with [sin] and [cos]...

I don't know why, but I had assumed that you wanted to plot something 
"parametrically", such as a path drawn from x(t) and y(t) functions, 
instead of a y(x) function. I was reading too fast.

For a y(x) function, sqrt(r*r-x*x) is the formula to use.

That is related to the fact that sqrt(1-x*x) = sin(acos(x)) = cos(asin(x)) 
where asin is anti-sin and acos is anti-cos.

It's also related to Pythagoras' theorem x*x + y*y = r*r which is also 
sin(t)*sin(t) + cos(t)*cos(t) = 1.

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| Mathieu Bouchard ---- tél: +1.514.383.3801 ---- Villeray, Montréal, QC


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