Musical instrument classification and some other woodwinds, such as the flute and bagpipe), other wind instruments such as the organ, and the stick-struck santur (a board zither). The distinction between fretted and open was in classic Persian fashion. Musical instrument classification Throughout history, various methods of musical instrument classification have been used. The most commonly used system divides instruments into string instruments, woodwind instruments, brass instruments and percussion instruments; however, other schemes have been devised. The oldest known scheme of classifying instruments is Chinese and dates from the 3rd millennium BC. It grouped instruments according to the materials they are made of. Instruments
Proof that e is irrational fraction, "e" is irrational. A short proof of the previous equality is known. Since the simple continued fraction of "e" is not periodic, this also proves that "e" is not a root of second degree polynomial with rational coefficients; in particular, "e" is irrational. The most well-known proof is Joseph Fourier's proof by contradiction, which is based upon the equality Initially "e" is assumed to be a rational number of the form ⁄. Note that "b" could not be equal to 1 as "e" is not an integer. It can be shown using the above equality that "e" is strictly