I need to do rotational (and other) transformations in an embedded application, requiring the sin() cos() and tan() functions. I know you can use look-up tables, and that's the only solution I could find doing my own research, but is there a good fixed point trig library out there?

I'm thinking of using a cortex M3 for the application, so I want to stay away from floating point as much as possible to keep applications zippy.

## Best Answer

A good approach for doing trigonometry in embedded applications is to use polynomial approximations to the functions you need. The code is compact, the data consists of a few coefficients, and the only operations required are multiply and add/subtract. Many embedded systems have hardware multipliers, giving good performance.