Re: atan2 and sqrt --> in driver

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Tue, Dec 09, 2008 at 06:01:52PM +0100, Robert Fritzsche wrote:
> The driver is for the wii-remote, so get 1 byte for x-, y- and z-axis.
> Based on this values I will calculate the pitch = atan2(y,
> sqrt(x^2+z^2)) and yaw = atan2(z, sqrt(x^2+y^2))

Two approaches: use integer math (e.g. fixed point) to approximate atan2
and sqrt. Alternatively, just provide a data table, indexed by 0..255 x
0..255, with the second operand shifted and the sqrt computed in integer
math. Search wikipedia for easy algorithms to compute isqrt.

Joerg