log(a)b=lg(b)/lg(a)

In fact, the formula for changing the bottom does not have to be changed to lg, but can also be changed to something else, such as:

Logarithm b = Logarithm b/ Logarithm A

It means that the numerator and denominator cardinality are taken at will, but they are all the same; The true number on the numerator is the original true number, and the true number on the denominator is the original radix.

Extended data application

Logarithm has many applications both inside and outside mathematics, some of which are related to the concept of scale invariance. For example, each chamber of the Nautilus shell is a rough copy of the next chamber, scaled by a constant factor. This leads to a logarithmic spiral. Benford's law about the distribution of pre-derivatives can also be explained by scale invariance.

Logarithm is also related to self-similarity. For example, the logarithmic algorithm appears in the algorithm analysis, and the algorithm is decomposed into two similar smaller problems, and their solutions are patched, and the problem is solved. The size of self-similar geometric shapes, that is, shapes whose parts are similar to the whole image, is also based on logarithm. Logarithmic scale is useful for quantifying the relative change of value relative to its absolute difference.

In addition, because the logarithmic function log(x) grows very slowly for larger x, the logarithmic scale is used to compress large-scale scientific data. Logarithm also appears in many scientific formulas, such as tsiolkovsky rocket equation, Fenske equation or Nernst equation.