Numerikus sorok - Index of
Numerikus sorok - Index of
Numerikus sorok - Index of
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1. Azonos értelmű egyenlőtlenségek összeszorozhatók:<br />
(α 1 β 1 )c n d n ≤ a n b n ≤ (α 2 β 2 )c n d n =⇒ a n b n = Θ(c n d n )<br />
2.<br />
3.<br />
0 < α 1 c n ≤ α n ≤ α 2 c n<br />
⎫<br />
⎪⎬<br />
0 < 1 1<br />
≤ 1 ≤ 1 1 =⇒<br />
⎪ ⎭<br />
β 2 d n b n β 1 d n<br />
tehát a ( )<br />
n cn<br />
= Θ<br />
b n d n<br />
( )<br />
α1 cn<br />
≤ a ( )<br />
n α2 cn<br />
≤ ,<br />
β 1 d n b n β 1 d n<br />
α(c n + d n ) ≤ α 1 c n + β 1 d n ≤ a n + b n ≤ α 2 c n + β 2 d n ≤ β(c n + d n )<br />
=⇒ a n + b n = Θ(c n + d n )<br />
α = min{α 1 , β 1 }, β = max{α 2 , β 2 }<br />
✓✏<br />
Pl.<br />
✒✑a n = √ 2n 2 + 3n + 1 − √ n 2 − n + 1 =<br />
=<br />
(<br />
Θ(n 2 )<br />
Θ(n) + Θ(n) = Θ(n2 )<br />
Θ(n + n) = Θ(n2 ) n<br />
2<br />
Θ(n) = Θ n<br />
✓✏<br />
Pl.<br />
✒✑a n = √ 7n 2 − 2n + 10 − √ 7n 2 − 2n + 3 =<br />
= Θ(1) ( ) 1<br />
Θ(n + n) = Θ =⇒ a n → 0<br />
n<br />
n 2 + 4n<br />
√<br />
2n2 + 3n + 1 + √ n 2 − n + 1 =<br />
)<br />
= Θ(n) =⇒ a n → ∞<br />
10 − 3<br />
√<br />
7n2 − 2n + 10 + √ 7n 2 − 2n + 3 =<br />
8.2. a n ∼ b n<br />
✎☞<br />
✍✌ D an aszimptotikusan egyenlő b n -nel, jelben a n ∼ b n , ha<br />
a n<br />
lim = 1<br />
n→∞ b n<br />
✓✏<br />
Pl.<br />
✒✑sin 1 n ∼ 1 sin 1 n<br />
, mert lim<br />
n n→∞<br />
1<br />
= 1<br />
n<br />
✓✏ ( n<br />
) n √<br />
Pl.<br />
✒✑n! ∼ 2πn Stirling formula (¬B)<br />
e<br />
c○ Kónya I. – Fritz Jné – Győri S. 33 v1.4