49 50 Ver6.09.hp Geodesic distance & Earth Euclidean distance calculator, bearing

[Gil]

I forgot to include

the subprogram ATAN2, whose location is the utmost parent directory HOME :

ATAN2

\<< \-> y x
\<<
CASE x 0 >
THEN '2*ATAN(y/(\v/(x^2+y^2)+x))'
END x 0 \<= y 0 \=/ AND
THEN '2*ATAN((\v/(x^2+y^2)-x)/y)'
END x 0 < y 0 == AND
THEN '4*ATAN(1)'
END x 0 == y 0 == AND
THEN "Undef"
END
END \->NUM
\>>
\>>

You might choose the alternative formula and program:

ATAN2

\<< \-> y x
\<<
CASE x 0 >
THEN y x / ATAN
END x 0 < y 0 \>= AND
THEN y x / ATAN -17 FS?
IF
THEN \pi
ELSE 180
END +
END x 0 < y 0 < AND
THEN y x / ATAN -17 FS?
IF
THEN \pi
ELSE 180
END -
END x 0 == y 0 > AND
THEN -17 FS?
IF
THEN \pi 2 /
ELSE 90
END
END x 0 == y 0 < AND
THEN -17 FS?
IF
THEN \pi NEG 2 /
ELSE -90
END
END "Undef"
END \->NUM
\>>
\>>

Note
\v/ stands for square root.

Regards,
Gil