Template:Calculate increment/doc

What it does
Calculates suitable increments for scalemarkers. Increments are 1, 2 or 5 raised to an appropriate power of 10.

Variable 1 = from; Variable 2 = to.

Problems it has
It doesn't deal with small (<10) scales yet.

How it does it
First we need to select the "base value" - i.e. what we're going to raise to the power of 10. We use the following brackets:
 * 14<35: 20
 * 35-70 : 50
 * 70->14: 10

To generate the first two digits is quite laborious. This code generates a suitably rounded number; we need to divide that by 10 n times.

Then we need to select the power of 10.