The sine wave or sinusoid is a function that occurs often in mathematics, signal processing, alternating-current power engineering, and other fields. Its most basic form is:

$y\; =\; A\; sin(omega\; t\; -\; varphi)$

peak deviation from center  = A (aka amplitude)

angular frequency $omega,$ (radians per second)

initial phase (t = 0) = −φ

φ is also referred to as a phase shift. E.g., when the initial phase is negative, the entire waveform is shifted toward future time (i.e. delayed). The amount of delay, in seconds, is φ/ω.