Table 2—The ArcTangent computation formulas for the various compass sectors become navigation data.

Keyword     Sector              ArcTangent formula

001             $00 – $20         $00 + $20 × DX/DY
000             $20 – $40          $40 – $20 × DY/DX
010             $40 – $60          $40 + $20 × DY/DX
011             $60 – $80          $80 – $20 × DX/DY
111             $80 – $A0         $80 + $20 × DX/DY
110             $A0 – $C0         $C0 – $20 × DY/DX
100             $C0 – $E0         $C0 + $20 × DY/DX
101             $E0 – $00         $00 – $20 × DX/DY