Re: Best way to compare CGFloats
Re: Best way to compare CGFloats
- Subject: Re: Best way to compare CGFloats
- From: Alastair Houghton <email@hidden>
- Date: Wed, 30 Jun 2010 10:14:48 +0100
On 30 Jun 2010, at 09:35, Rimas M. wrote:
> So question is, what is the most efficient (performance side) and
> simplest (coding side) way to compare those bastards?
>
> At the moment I am thinking about:
>
> a) BOOL _floatsOrDoublesAreEqual = ( (float)C.x == (float)D.x);
>
> b) BOOL _floatsOrDoublesAreEqual = ( fabs(C.x - D.x) <= _epsilon ); ,
> where _epsilon is something like 0.0001.
fabs is the right way to do this in most cases, *but* with co-ordinate values it may be that you are actually more interested in the distance of one point from the other---i.e. you might in fact be interested in
CGFloat dx = C.x - D.x, dy = C.y - D.y;
BOOL pointsAreEqual = (dx * dx + dy * dy) < epsilonSquared;
It rather depends on what you want, and that's going to differ from one application to another.
Kind regards,
Alastair.
--
http://alastairs-place.net
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