in reply to circular area in a coordinates grid (AoA)

This is one time I'd advocate not re-inventing the wheel. (Depends on how you are using your results.)

Graphics packages are contain very optimised fast circle drawing algorithms coded in C. So, define your "array" as a 2-color (BW) image and then have it draw the circles.

GD for example, can draw thousands of circles per second.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
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