(mathematics) The result that the Fourier transform is unitary; loosely, that the sum (or integral) of the square of a function is equal to the sum (or integral) of the square of its transform.

An island in Antigua and Barbuda. / An island in the British Virgin Islands. / An island in Trinidad and Tobago.

Bread made from wheat flour / (informal) whole-wheat bread (bread made from whole wheat flour)

A subdistrict of Hongshan district, Wuhan, Hubei, China. / A residential community in Zhuodaoquan, Hongshan district, Wuhan, Hubei, China.