[lisper]

How do you determine true north with a GPS system? GPS only gives you your position, not your orientation.

[chrisseaton]

> How do you determine true north with a GPS system?

  def true_bearing(magnetic_bearing, location)
    magnetic_bearing + gma(location)
  end

And that's the point - your true bearing is a function of your location.

[lisper]

Ah. Right. Duh. (I must be having an even worse day than I thought.)