+
+/* get the position and angle of the robot from the angle of the 2
+ * beacons, and the distance of 2 beacons */
+int8_t ad_to_posxya(point_t *pos, double *a, int algo,
+ const point_t *b0, const point_t *b1, /* beacon position */
+ double a0, double a1, /* seen angle of beacons */
+ double d0, double d1 /* distance to beacons */ );