Dictionary

In graphic representations of physical data, a way of plotting values according to their common logarithm. In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another fixed number, the base b, must be raised, to produce that number x. If the base is 10 then the logarithm of 10 is 1, the logarithm of 100 is 2, and so on.

In ordinary (“linear”) plots, the distance between the values 1 and 2 is the same as between the values 2 and 3. In a logarithmic plot, the distance between the values 1 and 10 is the same as the distance between 10 and 100 and the distance between 100 and 1000.