Fractional part

The latter is defined as the largest integer not greater than x, called floor of x or

Then, the fractional part can be formulated as a difference: The fractional part of logarithms,[2] specifically, is also known as the mantissa; by contrast with the mantissa, the integral part of a logarithm is called its characteristic.

[3][4] The word mantissa was introduced by Henry Briggs.

[5] For a positive number written in a conventional positional numeral system (such as binary or decimal), its fractional part hence corresponds to the digits appearing after the radix point, such as the decimal point in English.

The result is a real number in the half-open interval [0, 1).

However, in case of negative numbers, there are various conflicting ways to extend the fractional part function to them: It is either defined in the same way as for positive numbers, i.e., by

(Graham, Knuth & Patashnik 1992),[6] or as the part of the number to the right of the radix point

and the "odd function" definitions permit for unique decomposition of any real number x to the sum of its integer and fractional parts, where "integer part" refers to

These two definitions of fractional-part function also provide idempotence.