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visits member for 2 years, 11 months
seen Jul 26 at 19:45

I'm old. I get confused. OK?


Jul
26
comment What are some 'conceptualizations' that work in mathematics but are not strictly true?
Mathematicians are really sexy.
May
26
comment Can the square root of a real number be negative?
It appears to me that a part of the "problem" here is that the square root operation is relatively unusual in that it denotes the solution to an equation, whereas the vast majority of mathematical operations (at least the more familiar ones) do not. It's perfectly legitimate/un-scary for an equation to have multiple solutions, but we do not normally expect operators such as monadic - to produce multiple contradictory values. Thus there is some cognitive dissonance with the square root operator.
Apr
4
comment How can a piece of A4 paper be folded in exactly three equal parts?
Fold it into quarters and then tear away 1/4.
Nov
27
comment Dividing a range into major and minor divisions
I tried the scheme on for size and it works pretty well, thanks. It hadn't occurred to me that the number of variations was small enough to practically enumerate, and with this scheme certain "unpleasing" combos can be eliminated if desired, just by altering the table.
Nov
27
comment Dividing a range into major and minor divisions
I'll have to think about this one. I like the idea that, since everything is precomputed, it's inherently stable and testable.
Aug
30
comment matrices … why???
I agree that they're confusing, and, to the uninitiated, not at all intuitive. But the power of mathematics is that it condenses complex concepts down to (relatively) concise expressions, and those concise expressions are often easier to manipulate/solve than the more complex concepts. It's definitely a trade-off -- a "deal with the devil" -- but it's allowed civilization to progress rapidly for at least 500 years.
Aug
27
comment Why are “irrational numbers” not named “nonrational numbers”?
Because to do so would be irrational.
Aug
22
comment What does “calculus” mean in the most general sense?
Ask a dentist and he'll tell you it's the gunky buildup on your teeth.
Aug
22
comment Is there name for arithmetic mean divided by RMS average?
CV appears to relate mean to standard deviation, and I'm taking the ratio of mean and RMS average, which is not quite the same thing.
Aug
22
comment Is there a reasoning behind the depiction of the numbers as they are $\{1$, $2$, $3$, $4$, $5$, $6$, $7$, $8$, $9\}$?
I was always given to understand that the Babylonians had something to do with it. But I see Wikipedia lays most of the "blame" on the Hindu-Arabic numeral system. (According to that article using zero came fairly late in the evolution of the system.)
Aug
17
comment Need algorithm to take “max” of scores, but with “quality” weighting
@JoshuaShaneLiberman -- I'm not sure I understand the objectives completely, which is part of the problem. But there's an issue with the quality metrics I probably didn't explain very well -- I'll do that.
May
29
comment How to add or multiply decimal numbers?
The common way of adding decimal numbers is to use "excess-6" arithmetic, where 6 is added if the digit exceeds 9. There are various clever ways to do this, some more "clever" than they should be, but since the operation tends to be highly optimized the cleverness is usually merited.
Apr
3
comment Sheffer stroke the most important advance in logic?
It's worth pointing out that, in the parallel world of digital logic design, the NAND gate is considered to be the "universal" logical element -- any digital device you want to build can be built fron NAND gates. (And, in fact, this was often done.) I can imagine that if NAND gates had been invented fairly late in the development of digital electronics (rather than being just about the first thing invented) they would have been considered quite magical.
Apr
2
comment Pseudo Proofs that are intuitively reasonable
Other than the "gives the right answer" part, haven't you defined politics?
Mar
12
comment Exponential average of logs
@RahulNarain -- I've finally gotten the numbers to where they mostly stay positive, so mainly we're handling noise situations and "transitions". But it would be nice to have a general algorithm so I don't have to worry about discontinuities.
Feb
10
comment peak limiting/audio compression formula needed
Put that in an answer and I'll give you the check. Though I went over to DSP and got a suggestion of new_level = 10 * average * tanh(level/(10 * average)), which works pretty well.
Feb
9
comment What's the simplest curve that has an inflection point at zero and is asymptotic at 100.0?
I'd give you another +1 if I could. Came back to this thread seeking an answer to a question similar to the last one but a bit different and your answer gave me the hints I needed. Thanks!
Feb
5
comment Sum of averages vs average of sums
(When I get back to work on Monday I'm going to change the logic to use double-precision on the off-chance that the problem is due to losing precision. But it seems unlikely given the data.)
Feb
4
comment Sum of averages vs average of sums
This is C code, not a spreadsheet, and the numbers are "float" values, so no blanks. Pretty sure it's not a simple bug (though it may well be some sort of conceptual problem). The "sum" of the values in a row is actually accumulated separately from/concurrently with the individual values (though a check shows they add up to equal the sum), so taking the average of the row or some such is not the problem.
Feb
3
comment Sum of averages vs average of sums
(That is, the vertical time dimension is calculated with a moving average. FWIW, the column values tend to differ by a factor of 50 or so, with one column predominating.)