atan \*- arc tangent function
jsr r5,atan\fR[\fB2\fR]\fB
\fIatan\fR entry returns the arc tangent
from C, the arc tangent of \fIx\fR is returned.
The range is \*-\*p/2 to \*p/2.
The \fIatan2\fR entry returns the arc tangent
from C, the arc tangent of
The range is \*-\*p to \(*p.
There is no error return.