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The Lost Art of Logarithms

lostartoflogarithms.com

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Re: The Lost Art of Logarithms

#51

I found that looking at the original motivation of logarithms has been more elucidating than the way the topic is presented in grade-school. Thinking through the functional form that can solve the multiplication problem that Napier was facing (how to simplify multiplying large astronomical observations), f(ab) = f(a) + f(b), and why that leads to a unique family of functions, resonates a lot better with me for why lo…

This follows directly from the fact that exp(x+y)=exp(x)exp(y).

Re: The Lost Art of Logarithms

#53
post #24

Earlier quoted context omitted.

How long do I have to study math to understand this?

I love that you asked this, but I think it's not quite the right question. I've been wishing for years that someone would maintain a "dependency graph" for mathematical concepts. I think Khan Academy tried to do something like this at one point but took it down a long time ago. As long as we're far enough from the bleeding-edge of research topics, I feel like maths is the one field where this might be possible to do…

I had wanted to build a website like this as a hobby, except not limited strictly to mathematical concepts. I wanted to build a graph of the skills/concepts you’d need to understand electrical impedance, fix an air conditioning system, bake bread reliably.

One source of information could be course syllabi, which describe a progression of topics and their prerequisites.

Rather than be the authority on what concepts must precede others, I envisioned making a system that could represent different educational approaches: not every educator agrees that Calculus I ought to be a prerequisite for studying Physics I. Not all bread recipes use yeast.

I had a hard time finding a good domain for this effort. “Tree of knowledge” dot TLD was taken.

Re: The Lost Art of Logarithms

#55

Earlier quoted context omitted.

shouldn't it be var actualSize = 1 ?

Nope. I don’t know why the Java folks decided not to use the fairly standard verb “isolate” for this method, but that’s what it is[1]: > public static int highestOneBit(int i) > Returns an int value with at most a single one-bit, in the position of the highest-order ("leftmost") one-bit in the specified int value. Returns zero if the specified value has no one-bits in its two's complement binary representation, that…

Thanks. What a weird API.

Re: The Lost Art of Logarithms

#56
I feel frustrated that we cannot conceive of numbers like 10^80 (atoms in the universe) or 10^4000 (number configurations for a system with 4000 variables having 10 states each). Maybe there are superbrains out there in the universe that can do so.

Re: The Lost Art of Logarithms

#57

I found that looking at the original motivation of logarithms has been more elucidating than the way the topic is presented in grade-school. Thinking through the functional form that can solve the multiplication problem that Napier was facing (how to simplify multiplying large astronomical observations), f(ab) = f(a) + f(b), and why that leads to a unique family of functions, resonates a lot better with me for why lo…

I think this should be front and center. To that end I propose "magnitude notation"[0] (and I don't think we should use the word logarithm, which sounds like advanced math and turns people away from the basic concept, which does make math easier and more fun).

https://saul.pw/mag

Re: The Lost Art of Logarithms

#58
post #56

I feel frustrated that we cannot conceive of numbers like 10^80 (atoms in the universe) or 10^4000 (number configurations for a system with 4000 variables having 10 states each). Maybe there are superbrains out there in the universe that can do so.

I guess you have to define what you mean by "conceive".

I'm not sure you can even conceive a number like 1,000, if you're talking about holding an intuitive visual understanding in your mind at once.

Like, I can easily see 100 in my mind's eye as a 10x10 grid of circles. Even if I don't see each one clearly, I have a good sense of the 10 on each edge and the way it fills in. But ask me to imagine 10 of those side-by-side to make 1,000, and I don't think I can. Once I imagine the 10 groups, each one is just a square simplification, rather than any individual pieces within.

But I'm totally familiar with 1,000 as a concept I can multiply and divide with, and I can do math with 10^80 as well. And I can do so fairly "intuitively" as well -- it's just all the numbers up to 80 digits long. Even 4,000 digits fits on a single page of a book.

Re: The Lost Art of Logarithms

#59
post #56

I feel frustrated that we cannot conceive of numbers like 10^80 (atoms in the universe) or 10^4000 (number configurations for a system with 4000 variables having 10 states each). Maybe there are superbrains out there in the universe that can do so.

To me it's hard because we don't come across these magnitudes on a daily basis. Grains of sand on a beach is an off the top of my head way to visualize such quantities. But yeah, numbers that big, are so big that we have nothing to compare them with.

Re: The Lost Art of Logarithms

#60

I found that looking at the original motivation of logarithms has been more elucidating than the way the topic is presented in grade-school. Thinking through the functional form that can solve the multiplication problem that Napier was facing (how to simplify multiplying large astronomical observations), f(ab) = f(a) + f(b), and why that leads to a unique family of functions, resonates a lot better with me for why lo…

This follows directly from the fact that exp(x+y)=exp(x)exp(y).

Yes, but such a property was not available to Napier, and from a teaching perspective, it requires understanding exponentials and their characterizations first. Starting from the original problem of how to simplify large multiplications seems like a more grounded way to introduce the concept.
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