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Re: [ft-devel] Fast bisecting BBox_Cubic_Check

From: Alexei Podtelezhnikov
Subject: Re: [ft-devel] Fast bisecting BBox_Cubic_Check
Date: Wed, 27 Feb 2013 07:14:32 -0500

> The new code is a bit worse but faster. The problem is in the
> rounding.  I can potentially scale up the outlines temporarily to
> deal with this problem.

I really wonder whether it makes sense to speed up the exact bbox
computation if this causes a loss of precision.

The original motivation was to kill the last use of FT_SqrtFixed. Then I read old emails that made perplexing assertion that bisection is too slow to converge while never questioning iterations in the sqrt algorithm. So I saw a challenge and produced a fast proof-of-concept code without sqrt. It is a matter of improving accuracy now. The old algorithm uses upscaling to achieve its precision and so can I.

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