Description:
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On a system of Window XP, PHP/5.3.0 and GD 2.0.34 the imageellipse() function fails to draw a circle properly when dealing with large dimensions.

Calling the function for a circle with radius over 1032 pixels (an ellipse with equal width and height over 2064 pixels) creates a deformed circle with bumps in four directions. Increasing the dimensions makes things worse.

On a system of Linux, PHP/5.2.13 and GD 2.0.34 the issue does not appear.

Test script:
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<?php

header ("Content-type: image/png");
$im = imagecreatetruecolor(2200, 2200) or die("Cannot Initialize new GD image stream");
imagefill($im, 0, 0, imagecolorallocate($im, 255, 255, 255));
imageellipse($im, 1100, 1100, 2064, 2064, imagecolorallocate($im, 0, 0, 255));
imagepng($im);
imagedestroy($im);

?>

Expected result:
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A relatively smooth circle is drawn.

Actual result:
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The resulting circle has irregular bumps in it.