Asymptote Article Index for
Asymptote
Articles about
Asymptote
 

Information About

Asymptote




An asymptote is a straight or curved Line which a curve will approach arbitrarily closely, but never touch.

A specific example of asymptotes can be found in the asymptote (such as the preceding example's ''x'' = 0, which has an undefined Slope ) could be said to approach an " Infinite Limit ," while a curve approaching a Horizontal line (such as the previous example's ''y'' = 0) could be said to approach a Limit at infinity.

Asymptotes need not be parallel to the ''x''- or ''y''-axis, as shown by the graph of ''x'' + ''x''−1, which is asymptotic to both the ''y''-axis and the line ''y'' = ''x''. When an asymptote is not parallel to the ''x''- or ''y''-axis, it is called an oblique asymptote.

Asymptotes, especially vertical asymptotes, also do not need to go to infinity when approached at both sides. Asymptote x=a is a vertical asymptote for f(x) if it just satisfies ''either'' of the following conditions:

# \lim_{x o a-} f(x)=\pm\infty
# \lim_{x o a+} f(x)=\pm\infty

Note that ''f''(''x'') need not be undefined at ''a''. For example, consider the function

:f(x) = \begin{cases} 1/x & x
eq 0 \ 5 & x = 0 \end{cases}

As both \lim_{x o 0+} f(x) = \infty and \lim_{x o 0-} f(x) = -\infty, ''f''(''x'') has a vertical asymptote at 0, even though f(0) = 5.

A function ''f''(''x'') can be said to be asymptotic to a function ''g''(''x'') as ''x'' → ∞. This has any of four distinct meanings:

# ''f''(''x'') − ''g''(''x'') → 0.
# ''f''(''x'') / ''g''(''x'') → 1.
# ''f''(''x'') / ''g''(''x'') has a nonzero limit.
# ''f''(''x'') / ''g''(''x'') is bounded and does not approach zero. See Big O Notation .

See also Asymptotic Analysis , but contrast with Asymptotic Curve