## zondag, oktober 30, 2011

### Logarithmic Scales

At the moment, I'm learning a bit more about Logarithms. It's an interesting concept, especially because Business Objects has it and so far, I have never explained it, except how to switch it off.

First off, I never had much math in school, so I had to find out what Logarithms are and so I did, and it's great stuff.

I didn't know that Logarithms used to be the way (up to the 1970's) how people multiplied or calculated Powers. All done by using Logarithm tables.

In case you are one of those people who don't know what Logarithms are. Here's the deal.

In fact, there are several types of Logarithms, but the most common one is 10-based. (If you ever hear someone mention Natural Logaritms, that's another one, based on 'e').

A logarithm is the power 10 has to be calculated with, in order to reach a given number.

So, Log(100) = 2 because 10 to the power of 2 = 100.

What this gives you is a way to reduce numbers and keep their proportions. But that was not entirely what I was after. I wanted to know how a Logarithmic scale worked.

On a decimal scale, 1, 2, 3 all have the same interval: 1. So you would get a straight line.

On a Logarithmic scale, the difference between 1,2 and 3 is calculated by proportion.

When a number goes from 1 to 2, it has actually doubled, when it goes from 2 to 3, it has been multiplied by 1,5 from 3 to 4, it has been multiplied by 1,3. So in stead of a straight line, you would get a curve that indicates the proportional difference between numbers.

This is especially useful when you're looking at numbers that are far apart. Stock market information for instance can be displayed much more accurately with Logarithmic scale charts.

But I'll be looking into this a lot more in the near future.

Binabik