今日聽seminar時忽發奇想,不如在這裏玩一個遊戲(要大家參與的)。數學上有很多重要的函數,其中一個就是logarithm(這裏不管是、還是都可以)。這個函數涉及的範疇科目包括數學、物理、化學、計算機科學、各種工程學、天文學、金融等等。我想大家可以在這裏接力每人列三個logarithm出現的地方,看看可以去到幾長。
我先開始吧:
1)
2) 一種不穩定的物質進行radioactive decay。若它在k秒內質量由1變成,則該物質的half-year為秒
3) 絕大部分在現實使用將數字排序(sorting)的算法(algorithm),其運算時間為
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規則:每人只可以列最多三個,但少一些是可以的(就是說你只想到一個,就列一個吧)。
2009年11月26日 星期四
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6 則留言:
化學:
pH = -log [H+]
物理:
dB = 10*log(I/Io)
黎克特制~
Hyperbolic Geometry:
metric of the half plane
Applied maths:
Logarithmic spiral
Thermodynamics or information theory:
Entropy and Stirling's approximation
Optics:
Optical thickness and skin depth
Astronomy:
Magnitude of stars
(and hence in general,
Stevens' power law)
Palermo Technical Impact Hazard Scale, or Torino Scale
Cartography:
Mercator projection
Accounting or Auditing:
Benford's law
Music:
frequency of pitches
basically whenever you have an exponential, you are associated with a log
P.S.
There's a matrix inversion method described in Numerical Recipe. The computational cost of which scales as N^{log_2 7}, compare to LU in N^3
play game, u need to read the rule first :)
Prime Number Theorem
number of primes < x ~ x/ln(x)
Fractals
In calculating the fractal dimension by "box dimension"
Thermodynamics/Statistical Mechanics
Boltzmann entropy, von Neumann entropy
(application:Clausius-Clapeyron equation, Chemical Reaction Rate, ...)
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