Once you get the magnetic sensors the usual way to make a compass is to have two sensors at right angles to each other. You take the arctan of the two readings. Since you want such high accuracy, you will probably have to include a calibration table to make corrections.
The other problem will be the effects of the magnetic field being not parallel to the surface of the earth. You may need to have a third magnetic sensor and do more complex math and use a more complex correction table.
If I want to use magnet*oresistive sen*sors like as ho*neywell sensors for "where you are",can I assign a point as refrence and measure the distance from it?or get the coordinate of other points relative to that reference point?