When iterating to compute this quantity, the HIO algorithm provides feedback information to prevent stagnation. An iterative error reduction algorithm that measures this quantity, which requires measurements of both the object function and its Fourier transform, is named for Gerchberg and Saxon. MAD and SAD are two methods for retrieving this quantity while (15[1])employing (*) X-ray crystallography. Changing this quantity for a wavefunction results in no change in the expectation values of an observable. Optical path difference is used to measure this quantity using an interferometer. Destructive interference occurs when this property of the two waves is 180 degrees apart. (10[1]-5[1])The quantity, together with amplitude, specifies a wave. For 10 points, identify this property, which measures the left or right-ward shifts of a wave. ■END■ (10[1])