Translations:D’Alembert’s solution/6/en

is the general solution of the 1D wave equation, where $f\left(\cdot \right)$ and $g\left(\cdot \right)$ are arbitrary functions. This solution is known as the d’Alembert formula. The letter f is the standard notation for a mathematical function, and this usage will always be so. However, we already have used the letter f for the frequency, and that can lead to confusion. An alternative would be to denote frequency by the Greek letter v (lowercase nu), which is done in Sheriff’s Encyclopedic Dictionary of Applied Geophysics (Sheriff, 2002). However, the Greek nu looks too much like the letter v, which is used for velocity. Because the meaning should be clear from the context, in this book we will use the letter f both as a symbol for a mathematical function and as a symbol to denote frequency. A rose is a rose is a rose. In other words, things are what they are.