As a mathematical constant, e is the basis of natural logarithmic function. Sometimes it is called Euler number, named after the Swiss mathematician Euler. There is also a relatively rare name Napier constant to commemorate the introduction of logarithm by Scottish mathematician John Napier.

It is one of the most important constants in mathematics, just like pi and imaginary units I and E. The first mention of the constant e is a table in the appendix of John Napier's logarithmic works published in 16 18.

But it didn't record this constant, only a list of natural logarithms based on it, which is generally believed to be made by William Oughtred. It was Jacob Bernoulli who first thought that e was a constant.

Extended data:

It is really unknown to use e to express it, but it may be because e is the first letter of the word index. Another view is that A, B, C and D have other common usages, and E is the first available letter.

However, it is unlikely that Euler chose this letter because it is the initials of his own name, because he is a very modest person and always properly affirms the work of others.

The important point of exponential function based on E is that its function is equal to its derivative. E is an irrational number and a transcendental number. It is the first transcendental number to be proved, and it is not deliberately constructed.

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