Editing Nonstandard calculus (section)

==Limit==
While the thrust of Robinson's approach is that one can dispense with the approach using multiple quantifiers, the notion of limit can be easily recaptured in terms of the [[standard part function]] '''st''', namely

:<math>\lim_{x\to a} f(x) = L</math>

if and only if whenever the difference ''x''&nbsp;&minus;&nbsp;''a'' is infinitesimal, the difference ''f''(''x'')&nbsp;&minus;&nbsp;''L'' is infinitesimal, as well, or in formulas:

:if st(''x'') = ''a''&nbsp;  then st(''f''(''x'')) = L,

cf. [[(ε, δ)-definition of limit]].