Trig performance test

I have asserted that trigonometry is slow in a number of posts. The whole point of a post on Trig-free rotation blending is that trigonometry is so slow that it should be avoided. My reasons for this are my experiences on previous platforms, where trigonometric functions are often tens or hundreds of times slower than arithmetic operations.



But such assumptions often prove false on new platforms. Flash in particular does not have the highly optimised arithmetic operations of modern CPUs, so rather than trigonometry being especially slow it could be that maths in Flash is slow enough that there's no need to avoid Flash. This is certainly worth knowing, as there's no point avoiding particular functions if they are as fast as other ways of doing the same thing.

Half-angle formulae

The half-angle formulae are formulae from trigonometry with a variety of uses. One important use is for optimising trigonometric calculations, of the sort often used in 2D geometry. In particular calculations of the form


fSin = Math.sin(fAngle);
fCos = Math.cos(fAngle);


can be done more efficiently.