Vector Basic Interpreter Basic 80 Reference Manual - page 115
of
190
aR,
Extended,
Disk
Returns
the
arctangent
of X in radians.
Result
is in the
range
-pi/2
to pi/2.
The
expression
X
may
be
any numeric
type,
but
the
evaluation
of
ATN
is always
performed
in single
precision.
10 INPUT X
20 PRINT
ATN (X)
RUN
?
3
1.24905
Ok
10 A =-
454.67
20 PRINT
A;CDBL(A)
RUN
454.67
454.6700134277344
Ok