# How to compute similarity between two numbers

Is there some metric for computing similarity between two numbers which takes values in the interval $[0, 1]$?

I want something like:
$sim(1,1) = 1$
$sim(1,2) = 0.5$
...
...
$sim(50,47) = 0.78$
$sim(100,99) = 0.99$

If two numbers are small, then similarity is sensitive. But, if two numbers are big, then similarity is less sensitive.

Is there some metric like that?

• Have you tried dividing the small number by the large one? It seems to do exactly what you're asking for in three of your four examples. – Arthur Oct 15 '15 at 12:18
• you are right. I use "min(num1,num2) / max(num1, num2)" and it have the property that i want. thanks. – jin-seo.lee Oct 19 '15 at 2:13