ANDREW'S W.C.
the universe from a nutshell
Tuesday, February 22, 2011
Monday, February 21, 2011
Monday, February 14, 2011
Saturday, February 12, 2011
What is a logarithm?
Logarithms (or log for short) are highly useful in science, but they scare people a lot.
Imagine a function f(x) that takes x and does something to it.
Another function, g(x) "undoes" what f does.
In other words,
g[f(x)] = x
In English, if you hit x with f and then hit it with g you have come right back to where you started - it's like adding two and then subtracting two from a number. In math, we call f and g inverse functions.
Now, let's define what f does.
f(x)=10^x
So now, we define f so that it raises 10 to whatever x is.
NOW THE FUN PART! What is the g, the inverse function of f?
It is by definition a logarithm!!!!!!!!!!!!!!!!!!!
g(x)=log(x)
Let's do an example.
What is log(10^3)? Well the answer is obvious: 3! (Remember this can be rewritten as g[f(3)] which is, by definition, just 3.
Normally, logarithms are base 10 like the example, but we can define them to be base anything. Other popular logs are base e and base 2. (e is a number kinda like pi. It is roughly 2.71)
Imagine a function f(x) that takes x and does something to it.
Another function, g(x) "undoes" what f does.
In other words,
g[f(x)] = x
In English, if you hit x with f and then hit it with g you have come right back to where you started - it's like adding two and then subtracting two from a number. In math, we call f and g inverse functions.
Now, let's define what f does.
f(x)=10^x
So now, we define f so that it raises 10 to whatever x is.
NOW THE FUN PART! What is the g, the inverse function of f?
It is by definition a logarithm!!!!!!!!!!!!!!!!!!!
g(x)=log(x)
Let's do an example.
What is log(10^3)? Well the answer is obvious: 3! (Remember this can be rewritten as g[f(3)] which is, by definition, just 3.
Normally, logarithms are base 10 like the example, but we can define them to be base anything. Other popular logs are base e and base 2. (e is a number kinda like pi. It is roughly 2.71)
Thursday, February 10, 2011
Quote of the Day
"Hello. My name is Stephen Hawking, physicist, cosmologist, and something of a dreamer. Although I cannot move, and I have to talk through a computer, in my mind I am free!"
- Stephen P. Hawking
- Stephen P. Hawking
Riveting Riddles
The more you take away, the bigger it becomes. What is it?
scroll down for answer
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a hole
scroll down for answer
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a hole
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