atan -- r7rs Definition procedure;
Procedure variants:
((real-not-nan) -> (real-not-nan))
real-not-nan;real-not-nan;((complex-not-nan) -> (complex-not-nan))
complex-not-nan;complex-not-nan;((number) -> (number-nan))
number;number-nan;((real-not-nan real-not-nan) -> (real-not-nan))
real-not-nan;real-not-nan;real-not-nan;((complex-not-nan complex-not-nan) -> (complex-not-nan))
complex-not-nan;complex-not-nan;complex-not-nan;((number number) -> (number-nan))
number-nan;scheme:inexact -- (scheme inexact);scheme -- (scheme);Please refer to
exp.