Floor and ceiling functions - Wikipedia

The integral part or integer part of a number (partie entière in the original) was first defined in 1798 by Adrien-Marie Legendre in his proof of the Legendre's formula. Carl Friedrich Gauss introduced the square bracket notation [x] in his third proof of quadratic reciprocity (1808).[3] This remained the standard[4] in mathematics until Kenneth E. Iverson introduced, in his 1962 book A Programmin

[kazutanaka]

切り上げ、切り下げを floor, ceil で表現する方法は、1960年代にKenneth Iversion が考案したもの。APLの人。