常用数学术语和符号.
2006-04-21 23:21
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Asymptotic notation 渐进符号
Θ-notation - Asymptotic tight bound读法:Θ(n2) - pronounced "theta of n-squared".
意义:For a given function g(n), we denote by Θ(g(n)) the set of functions
Θ(g(n)) = {f(n) : there exist positive constants c1, c2, and n0 such that 0 ≤ c1g(n) ≤ f(n) ≤ c2g(n) for all n ≥ n0}.
(Within set notation, a colon should be read as "such that.")
O-notation - Asymptotic upper bound
读法:O(g(n)) - pronounced "big-oh of g of n" or sometimes just "oh of g of n".
意义:For a given function g(n), we denote by O(g(n)) the set of functions
O(g(n)) = {f(n): there exist positive constants c and n0 such that 0 ≤ f(n) ≤ cg(n) for all n ≥ n0}.
Ω-notation - Asymptotic lower bound
读法:Ω(g(n)) - pronounced "big-omega of g of n" or sometimes just "omega of g of n")
意义:For a given function g(n), we denote by Ω(g(n)) the set of functions
Ω(g(n)) = {f(n): there exist positive constants c and n0 such that 0 ≤ cg(n) ≤ f(n) for all n ≥ n0}.
Monotonicity 单调性
A function f(n) is monotonically increasing if m ≤ n implies f(m) ≤ f(n).
A function f(n) is monotonically decreasing if m ≤ n implies f(m) ≥ f(n).
A function f(n) is strictly increasing if m < n implies f(m) < f(n).
A function f(n) is strictly decreasing if m < n implies f(m) > f(n).
Floors and Ceiling 底和顶
For any real number x, we denote the greatest integer less than or equal to x by ⌊x⌋ (read "the floor of x") and the least integer greater than or equal to x by ⌈x⌉ (read "the ceiling of x"). For all real x,