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limit/return

values returned by limit

 Calling Sequence limit(f, point, dir, parametric)

Parameters

 f - algebraic expression point - equation, $x=a$, where x is a name and a is the limit point dir - (optional) direction; either left, right, real (default) or complex parametric - (optional) literal name

Description

 • The meaning of a returned infinity depends on dir. If dir is complex, then infinity denotes complex infinity.  Otherwise, the result infinity denotes real positive infinity, and -infinity denotes real negative infinity.
 • If limit returns a numeric range it means that the value of the limiting expression is known to lie in that range for arguments restricted to some neighborhood of the limit point.  It does not necessarily imply that the limiting expression is known to achieve every value infinitely often in this range.
 • If the limit is known to be undefined, or each side of a two-sided limit has a different value, or for a multi-dimensional limit the limiting value depends on the direction from which the limit is approached, then undefined is returned.
 • If limit is unable to evaluate the limit, then it returns unevaluated. Unless the limit is unevaluated, the limit returned is independent of the variable given in point.
 • When option parametric is specified, often a piecewise expression is returned. One of the branches in this piecewise expression (typically the last one, or otherwise branch) may be an inert Limit.

Examples

 > $\mathrm{limit}\left(\mathrm{exp}\left(x\right),x=\mathrm{\infty }\right)$
 ${\mathrm{\infty }}$ (1)
 > $\mathrm{limit}\left(\frac{1}{x},x=0,\mathrm{complex}\right)$
 ${\mathrm{\infty }}{+}{\mathrm{\infty }}{}{I}$ (2)
 > $\mathrm{limit}\left(\mathrm{sin}\left(\frac{1}{x}\right),x=0\right)$
 ${-1}{..}{1}$ (3)
 > $\mathrm{limit}\left(\mathrm{exp}\left(x\right),x=\mathrm{\infty },\mathrm{real}\right)$
 ${\mathrm{undefined}}$ (4)
 > $\mathrm{limit}\left(\mathrm{tan}\left(x\right),x=\mathrm{\infty }\right)$
 ${\mathrm{undefined}}$ (5)
 > $\mathrm{limit}\left(ax,x=\mathrm{\infty }\right)$
 ${\mathrm{signum}}{}\left({a}\right){}{\mathrm{\infty }}$ (6)
 > $\mathrm{limit}\left({x}^{a},x=\mathrm{\infty },'\mathrm{parametric}'\right)$
 $\left\{\begin{array}{cc}{0}& {a}{<}{0}\\ {1}& {a}{=}{0}\\ {\mathrm{\infty }}& {0}{<}{a}\\ \underset{{x}{\to }{\mathrm{\infty }}}{{lim}}{}{{x}}^{{a}}& {\mathrm{otherwise}}\end{array}\right\$ (7)