20121119, 02:23  #1 
6809 > 6502
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Aug 2003
101×103 Posts
2^{3}×1,117 Posts 
Interesting formulæ
Not sure if this belongs in the Lounge or Misc Math.
We all know several formulae, laws, or equations that relate to everyday life, that are not well documented by science. This thread is intended to be a place to document these. Submitted as the first is one that most all of us are well aware of: the need to urinate as a function of distance from a known restroom, with compensation for temperature and perceived velocity. u = need to urinate p = constant (5.7 in United_States customary units) d = distance to known restroom t = ambient temperature, the base formula given is for degrees Fahrenheit v = perceived velocity (1 = exactly 'appropriate' velocity, 2 = twice 'appropriate' velocity), no units required, autoadjusts for mode of transit. Those of you with medical training may be able to refine this. Below is a data table: Code:
d v t u 1.00 1.0 98.00 32 2.00 1.0 95.50 15 0.50 1.0 75.00 823 0.50 2.0 32.00 24858 1.00 2.0 98.55 16 1.00 4.0 98.55 8 0.25 1.0 75.00 26754 0.12 0.5 32.00 6091575835 0.10 1.0 32.00 55397617288 0.25 1.0 70.00 40965 0.12 0.7 50.00 706552439 
20121119, 17:00  #2  
"Forget I exist"
Jul 2009
Dumbassville
20C0_{16} Posts 
Quote:
1/((((b*w)/GFR)/B)*(d/vi)) is my best guess based on what I looked up,B= bladder capacity, b= blood volume, w = % waste by volume , GFR = glomerular filtrate rate, v and d have the same values as in your equation. this is one over percentage of bladder that can be filled in the time perceived to be needed to get to the known restroom. Last fiddled with by science_man_88 on 20121119 at 17:05 

20121119, 18:21  #3  
Bamboozled!
"𒉺𒌌𒇷𒆷𒀭"
May 2003
Down not across
3^{3}×5×7×11 Posts 
Quote:
Which to some may seem Rabelaisian, Let V be virginity,Let P be a constant persuasion. "Let V over P be inverted, With the square root of Mu inserted, N times into V ...Is a relative!" Einstein asserted. That one has been in the fortune(6) database for over 30 years. Last fiddled with by ewmayer on 20121119 at 18:56 Reason: "Virginity is like a balloon ... one prick and it's gone." 

20121203, 05:05  #4 
6809 > 6502
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Aug 2003
101×103 Posts
2^{3}×1,117 Posts 
Law of Dirty Rugs/Carpets: The chances of an openfaced jelly sandwich of landing face down on a floor covering are directly correlated to the newness, color and cost of the carpet/rug.
f=chance of jelly/carpet contact n=newness in months c=grayscale value of carpet color (0=completely nonreflective black, 1=completely white) d=cost of carpet in dollars m=monthly income in dollars 
20121203, 05:10  #5 
6809 > 6502
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Aug 2003
101×103 Posts
8936_{10} Posts 
Jilly's third law: The worse the haircut, the slower it grows out.
Jilly's second law (IIRC): Windspeed is proportional to the cost of the hairdo. Does anyone have the formulae for these? 
20121205, 01:08  #6 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
3·29·83 Posts 
This isn't exactly a formula, perhaps an algorithm.
With a divmod function, turning a total amount of time into certain amounts of smaller units is incredibly easy/beautiful. Code:
#eta is some large number of seconds days, eta = divmod(eta, 3600*24) hours, eta = divmod(eta, 3600) mins, eta = divmod(eta, 60) secs = eta if days > 0: print("days, hours, mins, secs") elif hours > 0: print("hours, mins, secs") else: print("mins, secs") 
20121208, 07:20  #7  
"Mark"
Feb 2003
Sydney
3·191 Posts 
This is even less like a formula; I came across it as one of the many corollaries of Murphy's Law. It went something like this:
Quote:


20121208, 07:51  #8  
Undefined
"The unspeakable one"
Jun 2006
My evil lair
2·3^{3}·109 Posts 
Quote:


20121208, 17:40  #9 
6809 > 6502
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Aug 2003
101×103 Posts
21350_{8} Posts 

20121210, 05:32  #10 
Basketry That Evening!
"Bunslow the Bold"
Jun 2011
40<A<43 89<O<88
16065_{8} Posts 
More gushing about Python.
Code:
def divisors(n): # Creates a list of all divisors of n # len(this list) == num_divisors(n) (includes 1) n = _positive(n, "divisors") if not isinstance(n, Factors): n = factor(n) # Create list by making a list of lists of prime powers for each prime # dividing n # Then take a "cartesian product" of all these lists, i.e. take all # combinations of one element from each list, i.e. take all combinations # of prime powers for each prime dividing n biglist = [] for prime in n: # Create list of all powers of a prime for each prime in n biglist.append([prime**power for power in range(n[prime]+1)]) # For 72 = 2^3 * 3^2, biglist = [[1, 2, 4, 8], [1, 3, 9]] # For 1800 = 2^3 * 3^2 * 5^2, biglist = [[1, 2, 4, 8], [1, 3, 9], [1, 5, 25]] divs = [1] # Now take all combinations of one element from each sub list # Or rather, take all combinations of the first list, then all combinations # with the second, etc. for lst in biglist: divs = [x*y for y in divs for x in lst] # That list comprehension syntax is *so* cool # For 1800: First iter: divs = [1*1, 1*2, 1*4, 1*8] = [1, 2, 4, 8] # Second iter: divs = [1*1, 1*3, 1*9, 2*1, 2*3, 2*9, 4*1, 4*3, 4*9, 8*1, # 8*3, 8*9] = [1, 3, 9, 2, 6, 18, 4, 12, 36, 8, 24, 72] # Third iter: divs = [1*1, 1*5, 1*25, 3*1, 3*5, 3*25, 9*1, 9*5, 9*25, # 2*1, 2*5, 2*25, 6*1, 6*5, 6*25, 18*1, 18*5, 18*25, 4*1, 4*5...] # and so on # All in one, nice, simple, list comprehension # Whew! return sorted(divs) # Sorting it is the least we can do :) Code:
>>> for i in range(50, 101): ... nt.divisors(i) ... [1, 2, 5, 10, 25, 50] [1, 3, 17, 51] [1, 2, 4, 13, 26, 52] [1, 53] [1, 2, 3, 6, 9, 18, 27, 54] [1, 5, 11, 55] [1, 2, 4, 7, 8, 14, 28, 56] [1, 3, 19, 57] [1, 2, 29, 58] [1, 59] [1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60] [1, 61] [1, 2, 31, 62] [1, 3, 7, 9, 21, 63] [1, 2, 4, 8, 16, 32, 64] [1, 5, 13, 65] [1, 2, 3, 6, 11, 22, 33, 66] [1, 67] [1, 2, 4, 17, 34, 68] [1, 3, 23, 69] [1, 2, 5, 7, 10, 14, 35, 70] [1, 71] [1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72] [1, 73] [1, 2, 37, 74] [1, 3, 5, 15, 25, 75] [1, 2, 4, 19, 38, 76] [1, 7, 11, 77] [1, 2, 3, 6, 13, 26, 39, 78] [1, 79] [1, 2, 4, 5, 8, 10, 16, 20, 40, 80] [1, 3, 9, 27, 81] [1, 2, 41, 82] [1, 83] [1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84] [1, 5, 17, 85] [1, 2, 43, 86] [1, 3, 29, 87] [1, 2, 4, 8, 11, 22, 44, 88] [1, 89] [1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90] [1, 7, 13, 91] [1, 2, 4, 23, 46, 92] [1, 3, 31, 93] [1, 2, 47, 94] [1, 5, 19, 95] [1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 96] [1, 97] [1, 2, 7, 14, 49, 98] [1, 3, 9, 11, 33, 99] [1, 2, 4, 5, 10, 20, 25, 50, 100] 
20121210, 06:35  #11 
6809 > 6502
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Aug 2003
101×103 Posts
2^{3}×1,117 Posts 
Dub, please reread the first few posts. Your's have been off topic.
Paul has gotten the right understanding. 
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