@staticmethod<EOL><INDENT>def horizontal_angle(C, P):<DEDENT>
S = Point(P - C).unit                   <EOL>alfa = math.asin(abs(S.y))              <EOL>if S.x < <NUM_LIT:0>:                             <EOL><INDENT>if S.y <= <NUM_LIT:0>:                        <EOL><INDENT>alfa = -(math.pi - alfa)<EOL><DEDENT>else:                               <EOL><INDENT>alfa = math.pi - alfa<EOL><DEDENT><DEDENT>else:<EOL><INDENT>if S.y >= <NUM_LIT:0>:                        <EOL><INDENT>pass<EOL><DEDENT>else:                               <EOL><INDENT>alfa = - alfa<EOL><DEDENT><DEDENT>return alfa<EOL>
Return the angle to the horizontal for the connection from C to P.
        This uses the arcus sine function and resolves its inherent ambiguity by
        looking up in which quadrant vector S = P - C is located.