528 reputation
315
bio website cobaltduck.info
location Milford, OH
age 43
visits member for 4 years, 2 months
seen 16 hours ago

A former math teacher for 10 years, converted to Software Engineering just a few years ago. Enjoy woodworking, kayaking, hiking, and geocaching.


Jun
20
comment How to solve a system of 2 equations in this form
This may also help you get started: en.wikipedia.org/wiki/Conic_section#Intersecting_two_conics
Jun
20
comment intersection of two graph
To put it simply, the graph of $f$ is a V shape, and each of the possible answers is a line. Choices A and B would look like $\underline{V}$, just with different amounts of space between the V and the underline, and choices C and D would look like V /, again just with different spacing between the V and the /. Only in choice E will the slash cut through the vee.
May
19
comment Why is 987654321/123456789 = 8.0000000729?
Unrelated, but ever notice that Sqrt(9.87654321) approximates pi? The number system is full of this kind of stuff.
May
12
comment How to represent the floor function using mathematical notation?
What do you mean by that big capital pi with all those other symbols around it? Can you describe that "without words" please? In your accepted answer, what does arctan mean? My point is, all notation was invented to describe some intellectual phenomenon, which may in turn have been based on some earlier idea, etc. until the whole thing ultimately boils down to cavemen telling how many mastadon had been successfully hunted by holding up fingers.
May
6
awarded  Caucus
Apr
2
comment Is 1+1 =2 a theorem?
The fact that I can describe a system (such as the integers modulo 2) where 1 + 1 = 0, would seem to suggest your statement cannot be a theorem.
Mar
21
comment Is there such a thing as proof by example (not counter example)
As a teacher of mine once said: beware Merten's Conjecture! en.wikipedia.org/wiki/Mertens_conjecture
Mar
7
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
Or, more generally, that the ultimate result of this digital summing is the same as the remainder when dividing by 9.
Jan
23
comment “How I wish I could calculate pi” analogs…
Citation needed?
Dec
31
comment How to answer a student objection to the use of “of” in pronouncing f(x)?
joriki "would have told the student to keep up the critical thinking." However Ben Crowell responds "it's time to grow up to a more mature intellectual level." Very interesting.
Aug
2
awarded  Yearling
Jul
8
answered Big List of Fun Math Books
Jun
22
comment Tuple definition
Have you checked the old stand-by for definitions? en.wikipedia.org/wiki/Tuple
Jan
18
answered Mathematical toys?
Nov
16
comment Functions over $R$ such that $f(xy) = f(x)f(y)$
There is a term for what you are asking about, 'totally multiplicative function': en.wikipedia.org/wiki/Completely_multiplicative_function
Oct
18
accepted Probability that Scouting ashes continue to circulate?
Oct
17
comment Probability that Scouting ashes continue to circulate?
So if I am understanding you, a fire may have on the order $10^{26}$ atoms of ash at the end, and I remove about $10^{24}$ atoms. If I model this as a binomial with $n = 10^{24}$ and $p = .01$, then my expected number of atoms from the original fire is $10^{22}$. After two fires, this goes down to $10^{20}$ and so on, until by fire number 12, my expected value goes below $10^{0}$. Makes sense, if my interpretation is correct?
Oct
17
awarded  Commentator
Oct
17
revised Probability that Scouting ashes continue to circulate?
adding clarification of Kolmogorov
Oct
17
comment Probability that Scouting ashes continue to circulate?
@Didier Piau: en.wikipedia.org/wiki/Kolmogorov_zero-one_law (edited question accordingly).