\PhiThe Greek letter \Phi (Phi) is often used in mathematics, physics, and engineering to represent various concepts. In mathematics, it can denote the golden ratio, Euler's totient function, or a generic angle in geometry. In physics, it might represent magnetic flux or work function, among other things. Its usage is context-dependent and can vary across different fields.
Represents the golden ratio in mathematics.
\Phi = \frac{1 + \sqrt{5}}{2}Euler's totient function, which counts the positive integers up to a given integer n that are relatively prime to n.
\Phi(n) = n \prod_{p|n} \left(1 - \frac{1}{p}\right)Represents magnetic flux in physics, where \mathbf{B} is the magnetic field and d\mathbf{A} is a differential area element.
\oint \mathbf{B} \cdot d\mathbf{A} = \Phi