Link: Mathematics

What is log

The log function isolates the exponent. It is the inverse function to exponentiation.

Example: 8 is the power of 2,

Zero and infinity

Note that = no value, because does not exist, even when is tiny, it’s not zero.

In R,

Application of : qPCR or real-time PCR

After each experiment, the measurement will double, therefore log function is useful.

Why is it useful?

It scale the axis of fold changes (quantity changes) to a symmetric scale, so it’s important to use a log scale when describing fold changes.

Arithmetric with log

  1. Multiplication can be converted to logs.

  2. Multiplication within log can be converted to addition


  3. Division converted to subtraction

  4. Division within log can be converted to subtraction